BackYard Chickens › Learning Center Articles › Hatching Eggs 101

Hatching Eggs 101


PS.... I am currently on the thread listed below....

don't be afraid to join us for your hatch, or to learn or start a bator build!

I WISH I HAD THAT OPPORTUNITY!  dont hesitate to pop on the thread and ask for help....

Click HERE: INCUBATING w/FRIENDS! come hatch, learn, Chat, Meet new Friends!



I have pulled extremely helpful NOTES, LINKS &

Informational Post Links from the incubation thread

for EVERYONE'S convenience and will continue to put them HERE:








Incubation Notes, Images, Videos & Links


BYC Member VIP Interview - Sally Sunshine




21 DAYS is just a baseline for hatching eggs.

See Chart below for details on the various species of fowl



Cool Videos Animation of Embryo Development...






Expected Hatch Rate

Don’t count your chickens before they are hatched, or even after for that matter!

Shipped eggs have a MUCH lower hatch rate.

The percent hatchability in the commercial poultry industry ranges from 78-88%.



Percent Fertility is the percentage of fertile eggs of all eggs set.

% Fertility   =    # of fertile eggs

                          # of total eggs set


Percent Hatchability is the percentage of fertile eggs which actually hatched out as live young.

% Hatchability =    # of eggs which hatch out

                               # of fertile eggs














 CREATOR: gd-jpeg v1.0 (using IJG JPEG v80), quality = 80


Choosing an incubator

Many different styles of incubators are available, most common are Styrofoam types found at most feed stores. These incubators hold more eggs and are usually less expensive, but they require more involvement in the hatching process. Egg turners are usually optional that can be added for convenience. There are also some great “hands free” incubators, commercial incubators as well as Simple Inexpensive Homemade Incubators. My husband and daughter made a “Coolerbator” it works 100% better than our store bought incubator because it has less than .5 degree variance and we have very successful hatches in it!

The Coolerbator link and how to make it…




  Links to help you decide on an incubator…….



Locate your incubator in a room in which temperature is 70 degrees, free from drafts,

away from windows and direct sunlight.

Did you know that the Incubating practice originated more than 2,500 years ago in Egypt and China. Methods of incubation were kept secret for a long time. In Europe attempts to use incubation are known from the 14th century. Owing to the imperfection of incubation apparatus (casks submerged in rotted manure, bakers’ ovens, and so on) and inadequate study of the conditions of incubation, it did not become common. Only since the end of the 19th and beginning of the 20th century, with the invention of better incubators, has incubation become widely used in Europe and the USA; since the middle of the 20th century it has been the principal method of propagating poultry.






An amazingly informative article on how eggs are formed



Egg defects and CORRECTIVE steps, several pages filled with detailed information

Optimum Egg Quality from your Flock:




Collection & Storage of Eggs

Sources for eggs are to search the BYC buy sell trade section, Craigslist and eBay. Your local thread on BYC may be the best bet for local eggs!

Look for your local site in the “Social section” “Where am I? Where are You!” on BYC. & 



The following Word File can be used when ordering shipped eggs, it is our suggestion that you copy/paste/edit to help you get the best eggs possible. Letter written by ozexpat

An open letter to egg shippers.doc 27k .doc file






Risks associated with hatching eggs of chickens



Choose eggs that are of good size, not abnormally big or small. Do NOT set dirty, cracked, or porous eggs. 

Clinical studies at the University of Arkansas have shown that if your going to set a dirty egg, set the dirty egg, DO NOT SAND, WASH OR WIPE dirty eggs as hatchability decreases with these practices!

Cuticula is the thin membrane that covers the whole eggshell that is made from the sticky fluid when laid which covers it and quickly dissolves due to carbondioxyde activity. 

This membrane can be penetrated by gasses but functions as a kind defensive mechanism to prevent the entry of bacteria.


 The washing and rubbing action also serves to force disease organisms through the pores of the shell. Place the eggs upright in an egg carton with the FAT, air cell end of the egg UP! Allow eggs to sit in a moderately cool, somewhat humid place for storage. Basements are great. Moderately cool means 55-65 degrees. Rotate your eggs a 3 times a day to keep the embryo from sticking. An easy way to turn all of the eggs at once is to place a thick book under one end of the carton, and later remove the book and put it under the other end of the carton, 3 times a day. Before adding eggs to the incubator always WARM eggs UP slowly to room temperature. IF THE EGGS ARE COLD Condensation can cause bacterial growth on the eggs! You can collect eggs up until 10 days or so, but after the 7th day lower hatch rates may result. 

Stored eggs take longer to hatch (about one hour per day of storage).

if you must wash using water warmer than the egg using warm water

as to not force bacteria into the egg( thermal properties) 1T bleach per gal.

It is important to ALWAYS wash your hands before handling your hatching eggs!


Omphalitis, yolk sack infection is caused by a bacterium that enters through the porous egg shell and easily kills embryo's and newly hatched chicks. Unfortunately, incubation conditions are ideal for breeding bacteria as well as incubating eggs. For more information on storing eggs refer to  Recommendations for hatching egg handling and storage


Egg Cleaning Procedures

for the Backyard Flock



note Tek-Trol Disinfectant Cleaner Concentrate is a better bleach alternative!



Is it Fertile or Infertile?

To check the fertility, simply break an egg in a bowl.

Find the white spot on the yolk. If you do not, use a spoon to gently flip the yolk over until you find it.

Bulls eye look is fertile.

  BOTH of these below ARE FERTILE!!

A link with more pics of fertile vs Non Eggs!



Clears at CANDLE are not always infertile!



Procedure for assessing flock fertility


A link with some good pics too! 






Record Keeping

Accurate and detailed records are very important in incubation.

In addition to records of individual eggs it is important to keep records of the temperature and the humidity, so that trends in temperature and humidity may be detected early and can be corrected for next hatch. 

Egg Details 19k .xls file


Incubating Chart 22k .xls file


unprotectedfieldscanbeeditedwithCAUTIONforfunctions.xls 306k .xls file

Here is a spreadsheet for the intense OCD hatcher there is a sample page and a workbook page


ozexpatbychatchtemplate.xlsx 20k .xlsx fileI suggest you save original and then hit "save as" a new file with your name and data





Egg Weights and Chick Weights

Breakout of Unincubated Eggs

10-14 Day Candling Analysis

Hatch Debris Analysis - Simplified Version




Incubation Chart

Here is a free app...

The following table lists incubation requirements for various species of fowl.



Incub. Period (days)

Temp (F.)¹

Do not turn




18th day




25th day




25th day

Muscovy Duck



31st day




25th day

Guinea Fowl



25th day




21st day




25th day

Bobwhite Quail



20th day

Coturnix Quail



15th day




20th day




22nd day




15th day


¹ Measured at degrees F. in a forced-air incubator. For still-air incubators, add 2-3 degrees F.
² Measured as degrees F. using a wet-bulb thermometer. Use chart to convert to relative humidity. (Quail) (Muscovy) (Turkey) (yinepu's Turkey)






Areas of MOST IMPORTANCE in Hatching EGGS

Ventilation (Oxygen), Temperature, Humidity, Egg Turning/Positioning








Ventilation is VERY important during the incubation process.

While the embryo is developing, oxygen enters the egg through the shell and carbon dioxide escapes. Oxygen requirements will increases during development and during hatching. Unobstructed ventilation holes, both above and below the eggs, are essential for proper air exchange. REMOVE RED VENT PLUGS, TOO MANY PEOPLE FORGET TO REMOVE THEM AT DAY 10!  NOTE: When Lockdown occurs, vent openings are frequently restricted in an attempt to boost incubator humidity. Instead of helping the chick hatch, the chick is suffocated from lack of oxygen. Never decrease ventilation openings at hatching in an attempt to increase humidity. Increase humidity by other methods. If any vent adjustments are made, they should be opened more. Try adding a dampened sponge or towel to help boost humidity during lockdown.



 Adjusting ventilation


Start to ventilate at a low level after 3-4 days of incubation to avoid relative humidity being higher than set point for too long.

Reducing ventilation at the start of incubation generally avoids the inlet of cold air. Because moisture is trapped in the closed incubator, the humidifier cold spot is also absent. Consequently closing the valves during the first days improves temperature homogeneity and heat transfer to the eggs, producing a good, uniform environment for continuing embryonic development – and an ideal start for achieving a narrow hatch window.

However at the same time, hatchery managers are aware that total weight loss may be challenged if ventilation is closed for too many days, with the result that relative humidity levels become too high. This is especially true in climates typified by high humidity.


Since eggshell is porous, the release of (water) vapour from the egg starts immediately after laying, continuing throughout egg handling, storage and the incubation of the eggs. Evaporation from the eggs - and thus weight loss - is mainly a physical process, driven by differences between internal and external vapour pressures. Internal vapour pressure is mainly represented by the saturation vapour pressure in the air cell, which increases as temperature increases - thereby facilitating increased evaporation (weight loss) at a certain relative humidity. In environments with high humidity, weight loss is limited. So for example if relative humidity in the setter reaches 75% , the daily weight loss of the eggs is only half of the weight lost from eggs placed in a setter with 50% relative humidity.

We can conclude, that closing ventilation for the first three to four days of incubation is beneficial, supporting uniform embryonic development for each egg in the incubator to facilitate a narrow hatch window. Subsequently, ventilation should be opened gradually to support optimum daily weight loss, by the continuous removal of moisture from the eggs.







Never trust the thermometer that comes with the incubator, always check it.

The thermometer that came with my incubator was off by 5 degrees.

That could mean life or death for your babies.


Did you know "The yolk is orange and on its surface is a visible germinal disc; radiating from this area is the more watery white

yolk, which is less dense. During turning, the yolk’s structure makes the part containing the germinal disc stay most dorsal (closest to the incubating bird) for heating"


With a Forced Air Incubator (fan model) you can get the best hatch rate by keeping the temperature at 99.5º F. throughout the entire incubation period. HOWEVER, when using a Still Air incubator (no fan) at 102º F. The reason for different temperatures is that with a fan model the circulating air warms all around the egg while still air temperatures are warmer at the top of the egg than at the bottom. The temperature is measured at the level where the embryos develop (at the top of the HORIZONTAL egg). NOTE:

If the eggs are in vertical position, elevate the thermometer just below the top of the egg. The temperature is measured at the level where the embryos develop (at the top of the egg). Never allow the thermometer to touch the eggs or incubator because incorrect readings can result.

A high temperature tends to produce early hatches. A consistently cooler temperature tends to increase incubation times and produce weakened chicks. In both cases the total chicks hatched will be reduced.  Prepare your incubator and run it for several days before adding eggs, to be positive you are maintaining correct incubation temperature.  NOTE: It is common that when adding eggs the temperature will drop but should come back up to correct temperature within an hour or two. Don’t rest the thermometer's bulb touching the eggs or the incubator. Incorrect readings will result. Did you know that 10/13 day old embryos begin to produce excess heat in the incubator? Most large commercial incubators will spend more time cooling than heating!


Why Measure eggshell temperature?




Calibrate the thermometer/s you are using for your Incubator. I use 3 thermometers! You need to make sure your thermometer is reading correctly, Even one degree may cause serious problems with your hatch!  A simple method without specialized instruments and knowledge is to compare your thermometer/hygrometer with other devices.


CALIBRATION of thermometers:

Freezing point method.

Fill a glass with crushed ice. Add a LITTLE clean water until the glass is full and stir. Wait 3 minutes then insert the thermometer tip into the ice-filled glass so it’s in the water ice mixture. Wait a minute and if the thermometer reads 32 F then it’s accurate, and if it does not, it requires calibration.


Boiling point method.

Boil water in a pot, about 6” deep. When the water is at boiling point, place the thermometer into the water and make sure that the tip stays in the middle of the boiling pot, away from bottom and sides. Wait 30 seconds and check if the thermometer reads correctly at 212 degrees if you are at sea level or below 1,000 feet elevation. The boiling point of water varies for different elevations: sea level at 212 F, 1000 feet at 210 F, 2000 feet at 208 F, 3000 feet at 206.4 F, 5000 feet at 202.75 F, and 8,000 feet at 197.5 F. The thermometer needs calibration if the reading is incorrect.


Calibrate the Digital Thermometer

Adjust the nut of the digital thermometer in order to correct the temperature. This is done by simply turning the adjuster until the correct reading is reached. Digital thermometers do not require any adjustment of a screw or nut. You simply need to locate the reset button. When the freezing point or boiling point of water is achieved, simply push the button and that’s it. Some digital thermometers may require you to push hold the reset button.


More information on Calibrating your thermometer/hygrometer: 







NOTE: Some incubators, even expensive ones may have "hot spots" or "cool spots" depending on air circulation inside the incubator.


Probe thermometer & water weasel (Water Wiggler, Water Snake) found on Amazon or Ebay make for EXCELLENT internal temp guides! The perfect internal temperature of an embryo is 99.5 degrees. If you can't find a water wiggler you can make your own with ziplock filled with water folded in half and insert the probe in the center middle.




Examples of thermometers and hygrometers

I personally like to keep a digital one that also keeps track of “highs and lows” along with 2 incubator thermometers AND a PROBE!  It depends on how scientific you plan your hatch!

More Important than make/model is CALIBRATION.






*                 *


WHAT YOU CAN DO to save overheated or cold eggs! 

What Temperatures Kill In An Incubator?  

WHAT If the Power Goes Off?


To understand more about embryo viability & temperatures

Please refer to the following links….

Brinsea ~ Temperature Guide

Temperature Chart pdf

BYC What to do if the power goes out!

Some other ideas to help maintain heat in your incubator and great when you turn by hand is by adding some sterilized rocks,

or even several sealed jars with warm water or small ziplock baggies with warm water to fill the empty incubator spaces. 

A full incubator of eggs always helps maintain a steady temperature even if it’s not good for your chicken math!

if the electric goes off, you have to do whatever you have to do to keep them warm, if you have to take them to someone that has electric or take them to the car to run them off the car battery. just be careful.

you should ALWAYS have a plan  and we also have a electric alarm if we loose electric!  you just plug it into an outlet and it sounds when you loose it! and its cheap!




Automatic 120db Power Cut Failure Outage Alarm Waring Siren with LED Indicator





Wagan SmartAC 210 Watt Power Inverter bag-of-rice-clipart-image.jpgdry rice heated on woodstove


handwarmers.jpg hot-water-bottle.jpeg?7489a8 







The Air Bubble in the Egg

DRY HATCH incubation DOES NOT MEAN RUN DRY!  It is not only the final size of the air cell that matters, but also the time it takes to form. In the first ten days of incubation, the embryo is small and floats in the amniotic fluid. Weight loss during this phase is mainly the effect of water evaporating from albumen and internal liquids. After this stage, changes occur quickly: the growing embryo gradually fills the egg, excepting the air cell. Low RH set points at days 14-18 of incubation increase evaporation from the allantois – and once the allantois is emptied of fluid, moisture will be drawn from the embryo, causing its dehydration. 

The average chicken egg has thousands of pores running through the shell allowing the embryo to exchange oxygen, carbon dioxide. and water. Soon after an egg is laid, a small air bubble or “air cell” forms in the large end of the egg from this water loss.  Humidity levels in the incubator determine moisture evaporation during the 21 days of incubation and hatching. The air cell is crucial for the chick to break out of the egg shell at the end of the incubation period. The chick can drown if the air cell is too small or the chick may be retarded in growth if the air cell is too large. This is why maintaining the proper humidity is crucial. Slightly lower humidity levels are more likely to be less disastrous than slightly higher humidity levels. There are quite a few opinions on Humidity, but it is no set number.

Humidity is NOT A SET NUMBER, you need it YES!

However, you use it as a tool to "adjust" egg weight loss during incubation. We candle on days 7,10,14,18 To WATCH WEIGHT LOSS IN EVERY EGG!  An EGG MUST lose approximately 13-14% of its weight during the incubation process. THIS IS YOUR GOAL!! You can monitor this by marking Air cells and also by weighing. Please refer to CANDLING section of this Article for more Air Cell info.


Size of air cell on day 7, 14, and 18 of incubation






I choose the easier method, keeping a close eye on air cell growth during incubation. You begin by ONLY adding a small amount of water and keep Humidity between 20%-30% and adjusting as you weigh or candle depending on moisture loss. IN SOME AREAS OF THE COUNTRY YOU MAY NOT NEED TO ADD ANY WATER! USE IT AS A TOOL FOR THE CORRECT WEIGHT LOSS IN THE EGG! So if your air cells look too large at each candle period you must add some humidity, too small air cell lower it, and if your weighing you adjust as needed. UNTIL DAY 18 LOCKDOWN,

then stop turning and raise humidity to 65-70%




Views of Day 18 Candle.....



How Does a Hygrometer Work?


Shown here is a WET Bulb Hygrometer and wick

Wet bulb is exactly what it states. It is the temperature relative of the humidity in degrees. 

A  Hygrometer Wick is placed over the stem of the thermometer and the other end of the sleeve is placed in a jar or pan in the incubator. 








NOTES: It’s a good idea to keep the incubator plugged into a surge protector. Use distilled water in your incubator to help prevent bacteria growth. Omphalitis, Mushy Chick Disease and Yolk Sack Infection may be caused by a bacterium that enters through the porous egg shell. Unfortunately, incubation conditions are ideal for breeding bacteria as well as incubating eggs. Brinsea sells a disinfectant, formulated to be used for cleaning eggs, incubators, safe and effective against yeasts, fungi, viruses and bacteria which can cause fatal damage to the growing embryo. Pennies can be added to water wells. Copper helps to destroy the cell walls of bacteria, thus keeping bacteria out of the incubator. Pennies before 1982 have more copper content and pure copper kills 99.9% of bacteria.



Below image is a Simple waterer/suctioner out of aquarium tubing placed through side of incubator and into water wells. Use a Kids medicine syringe to add/suck water without opening or disturbing eggs.


In the image below are the different sized cups I use the first 18 days of incubation INSTEAD of using the wells in the bottom of the incubator. I had a hard time getting humidity correct, so I started using different size containers and caps for water holding, I could easily remove & replace as necessary. It WORKS WELL and I can keep them clean and sanitized better and not disturb my eggs! I will remove these cups on day 18 so the chicks don’t drown in them

and use the lower wells at lockdown at day 18.


 2" funnel & we shoved it into a small piece of 1/4" tubing, a cleat on the inside of the unit (a wide-crown staple or cable staple would work also) to hold the tubing in place.  

This way you can add water to the middle of the bator without missing the water troughs and without opening the unit. see below
(Thanks tlpounds)





Surface area of water will increase humidity more so than depth!

If you need a safe boost at lockdown just add a dampened sponge or rag.

A "ShamWoW" is great as a wick and can hang from the sides or across top of incubator.





The influence of high altitude on the hatching of chicken eggs. 



The main problems facing chicken embryos when incubated at high altitudes are a reduced oxygen supply and dehydration.  The first priority when incubating eggs at high altitudes is to ensure that egg weight losses are correct (see Hatchery How To No.1 for recommendations on optimum egg weight loss). Based on the fact that water diffuses through the pores in the eggshell faster at altitude this would mean running a higher incubator humidity set-point. READ MORE :












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Setting Eggs & Turning

It is important to ALWAYS wash your hands before handling your hatching eggs!

It is likewise important to SANITIZE your incubator AND equipment before AND after use!

Omphalitis, yolk sack infection is caused by a bacterium that enters through the porous egg shell and easily kills embryo's and newly hatched chicks. Unfortunately, incubation conditions are ideal for breeding bacteria as well as incubating eggs.



REMINDER to see the Shipped eggs section of the article and to treat every shipped egg differently as its air cell is presented to you!

Failure to turn eggs during incubation CLEARLY

reduces hatchability in every scholarly study and every clinical trial.

Also SEE HERE for DETAILED Scientific explanations of WHY TURNING IS IMPORTANT!




Frequency of Turning, Angle of Turning, Smoothness/Gentleness of Turning

Increased Deaths
Sticky Chicks due to unabsorbed Albumen

The effects of turning during a critical period for turning, from 3 to 7 days of incubation, were also recorded. Generally, failure to turn eggs retarded growth of the area vasculosa. Turning during the critical period stimulated the extent of growth of the area vasculosa by day 7 of incubation and of subsequent embryonic growth by day 14. Incubation at low temperature resulted both in reduced expansion of the area vasculosa and retarded embryonic growth in a pattern similar to that observed for unturned eggs. It is suggested that turning stimulates development of blood vessels in the area vasculosa via localized increases in blood pressure.  


We were able to demonstrate that it is critical to turn eggs for at least the first three 
days of incubation and better for the first seven. READ MORE HERE  and HERE


Only add room temperature eggs to your incubator to prevent SWEATING. Sweating/Condensation weakens the egg's natural defense ­mechanisms, providing an ideal environment for the growth of bacteria and penetrated through the shell pores and kill the embryo.  Eggs can be laid on their sides or placed in turning tray with pointed end down/big air cell end up. For shipped eggs, please refer to SHIPPED EGGS section of this article.


Mark eggs, using a pencil, with an X on one side and an O on the other. Make sure to turn the eggs at least 3 times a day, or odd number of times. Turning by hand they should always be turned an odd amount of times and move them to a different part of the tray to protect them from temperature variation. You basically roll the eggs with your fingers/palm from X to O. It is important to NOT ROLL the eggs in the same direction every time. Improper rolling can cause the chalazae that holds the yolk in place to tear. Turning the egg prevents the embryo from touching and attaching to the membrane inside the egg. The most convenient way to turn eggs is to purchase an egg turner. Take extra precautions when turning eggs during the first week of incubation. The developing embryos have delicate blood vessels that rupture easily when severely jarred or shaken, thus killing the embryo. 



When adding Eggs the temperature will immediately drop. DO NOT ADJUST THE THERMOSTAT, or risk accidentally cooking them. Wait 2/4 hours and if the temperature is still low, make a small adjustment, as small as you can. (Note: Small adjustments on the manual Styrofoam incubators make BIG changes!)















Shipped Eggs = Change Of Plans!

Shipped eggs have a MUCH lower hatch rate, even with experienced hatchers! 

The following Word File can be used when ordering shipped eggs,

it is our suggestion that you copy/paste/edit to help you get the best eggs possible.



An open letter to egg shippers.doc 27k .doc file



 It’s always best to get local eggs to get the best hatch rate. Sources for eggs are to search the BYC buy sell trade section, Craigslist and eBay. Your local thread on BYC may be the best bet for local eggs! Look for your local site in the “Social section” “Where am I? Where are You!” on BYC. 



Rolls like a Carpenters Level





The yolk of an egg is held in place on each end by what is called Chalaza. These are delicate cords that keep the yolk centered in the egg. When you crack open an egg, you notice a white stringy thing on the yolk, this is the Chalaza. When eggs are shipped they encounter postal handlers that toss the packages, sorting machinery, bumpy vehicle rides, temperature changes and possibly X-ray Machines! So by the time the eggs get to you they are pretty much scrambled inside. So if you are going to buy eggs and have them shipped to you, be aware that the viability drops TREMENDOUSLY. There are rare instances when they ALL arrive safely but it is always a gamble.

See Egg anatomy here




CONCLUSION ~ Shipped eggs

If an egg has a normal intact air cell PLEASE TREAT IT AS A NORMAL EGG!



For rolling, detached or disrupted air cells

(cells no longer at fat end of the egg but like a bubble level on the long side, rolling or saddle shaped cells), you’ll need to change your hatch plan. These eggs need to sit and settle to room temp 12-24 hours NO TURNING, pointy end down in a Egg Carton to possibly reattach air cells.  


For SETTING in the incubator...... 


If your air cell is ROLLING end to end do not turn for 36-48 hours of the first incubation hours to help air cell re-attach and in some cases are really bad loose air cell should not be turned either, if after 48 hours and you have embryo growth and the air cell is still completely loose, do not turn another 24 hours.   


If air cells are saddle shaped but intact (meaning not jiggly) I put them in the turner and begin with the gentle turning or you can turn by hand in the carton by simply tilting side to side, see image below. 



I personally have found that any shipped egg that survives to day 18 lockdown has an awkward but re-attached air cell so I lay my eggs down for hatch.  Please refer to day 18 lockdown for more information on why laying eggs for hatching after day 18 is the best way to go. 


REMINDER~ Never Set COLD eggs in the incubator.




Below image are Eggs in A Carton with Bottoms cut out for Ventilation 



Below image of Turning damaged air cell Shipped Eggs, just lean to opposite side.


BELOW is a short video of an Rolling Detatched Air Cell




SHIPPED EGGS & Malpositions!



SADDLE SHAPED AIR CELLS are very COMMON with shipped eggs!

Saddle shaped is when one or both sides have a large "dip" in the air cell. A lot of times with saddle shaped cells the chick doesn’t position correct for hatching and their feet can easily get stuck behind their head and “smoosh” the chick so they can’t move, it can also force the yolk sack and everything more north in the shell.... Keep a close eye on these eggs and its VERY important to pencil mark Air cells!



 If you do receive a cracked egg and it’s an expensive egg you can try to hatch it, but beware of bacterial explosion and

good possibility of ruining other eggs. It is possible to hatch a cracked egg by sealing the crack with candle wax/crayon wax or finger nail polish. Try to place the egg in a cup or protected place well away from other eggs. If viable to hatch, keep a close eye on where the pip mark will be in case the chick cant get through a fixed area.


















Sites to refer to for Candling Images and Videos


Progression Though Incubation


Great pics of CANDLING and good and bad eggs.......


Metzer Candling :


Development of a Chick:


Candling Pics:


Understanding the Air Cell

The average chicken egg has thousands of pores running through the shell allowing the embryo to exchange oxygen, carbon dioxide and water. Soon after an egg is laid, a small air bubble or “air cell” forms in the large end of the egg from water loss.  Humidity levels in the incubator determine moisture evaporation during the 21 days of incubation and hatching. The air cell is crucial for the chick to break out of the egg shell at the end of the incubation period. The chick can drown if the air cell is too small or the chick may be retarded in growth if the air cell is too large. This is why maintaining the proper humidity is crucial. Slightly lower humidity levels are more likely to be less disastrous than slightly higher humidity levels.


MARKING and OBSERVING the size of the air cell is a way of checking for correct weight loss of the egg and is commonly used. However, this can be inaccurate due to the different, types, shapes, and ages of eggs. The protrusion of the embryo into the air cell also may effect observations. Again, it is the most common method for non-commercial hatchers. With experience you can adjust your humidity as needed by visual inspection of air cells. However, Weighing is the MOST accurate. If the incubation humidity is too low (very dry conditions), the air sac will be larger than normal and the humidity in the incubator should be increased to reduce the rate of water loss. If the air space is smaller than normal then the opposite applies.

Track the air sac with pencil tracings when you candle,

On the 7, 14 & 18th days  page 28  








Chicken eggs need to lose 13% moisture over 21 days, NOT day 18 lockdown. Weigh all the eggs on the first day, before you put them in the incubator and weigh again days 10, 14 & 18. Several formulas can be used to determine the rate of weight loss or overall per cent weight loss and to correct the humidity if the values are off. For accuracy, a digital scale should be used which can weigh in grams. Don't forget to subtract the weight of the container holding the eggs from the total weight when calculating the average egg weight. If you use a rack to incubate your eggs it is best to weigh the entire rack instead of each egg to get an average. If you are incubating SHIPPED eggs upright in a carton you will also weigh the entire carton so that the eggs are not disturbed.





Some Explainations from cochins1088 on weighing Eggs!

Eggs should lose approximately 11% - 12% of their mass at 18th day of incubation. To monitor mass loss, a person must keep track of an egg’s weight. Optimally eggs should be weighed right after they’re laid, but this isn’t always possible.  When eggs are shipped, weigh them as you remove them from the package.  Keep in mind that the eggs will lose some of their mass during storage. According to Aviagen, eggs lose about 0.5% of their masses per week in storage.


How to Calculate Mass Loss


First subtract the current weight of an egg from the original weight of the egg. This number will give you the weight loss. Then take the weight loss and divide it by the original weight of the egg.  This will give you the fraction of weight that was loss.  Lastly, multiply the fraction of weigh loss by 100.  This will give you the percent of mass loss.   


For example:


Original weight (50 g) - Current weight (45 g) = Weight lost (5 g)

Weight lost (5 g) divided by Original weight (50 g) = Fraction of weight lost (0.1)

Fraction of weight lost (0.1) multiplied by 100 = Percent of weight lost (10%)



For those of you who incubate large numbers of eggs, you can weigh the trays to find the average mass of each egg.


For example:


If a tray weigh of eggs initially weighs 700 grams and the empty tray weighs 200 grams, than the eggs must initially weigh 500 grams. If there are 10 eggs in the tray, then each egg weighs approximately 50 grams.

Let’s say that 2 eggs are removed because they were infertile.

After 18 days, your tray weighs 560 grams. If you subtract the weight of the tray (200 grams), than the eggs must weigh 360 grams. There are 8 eggs in the tray, so each egg weighs approximately 45 grams.

With this example, the eggs lost 10% of their mass by day 18.





For formulas used to determine the weight loss please refer to

                    Weight Loss Determinations:


Note: Kitchen scales work great. The WeighMax Pocket Mini CD Digital Scale below works great if you weigh individual eggs. I pasted an egg carton cup firmly to hold the eggs.  Be extremely careful not to tip your scale and crack your eggs!








 Always wash hands before handling eggs. 

The shell of an egg is thin and opaque when held near a bright light. The easiest type of egg to candle is the white shelled egg and some of the hardest eggs to candle are dark brown eggs, like the Maran eggs pictured below.


You could try two or more flashlights to see into them!





Candle days are 1, 7, 14 & 18th day

You will need a Candler, bright light, LED flashlight or build your own Candler. Find Instructions HERE.

Turn on your Candler and shut off the lights in the room so it is dark, evenings are best. Hold the flashlight/Candler like the image below and set the egg air cell/fat end down on your hand. This will prevent any light leakage from the flashlight. Your hand protects the egg from the hard surface of the light and helps more of the light to go through the egg.




CAUTION: Be very careful when you handle the egg

so you don't accidentally crack it or DROP it!


Slowly & gently rotate the egg until you can see inside the egg. On Day 1 candling you will mark air cells and check for cracked or porous eggs.  Lightly mark the air cell with a pencil. Candle quickly if the light gets hot, you will kill the embryo. On Day 1 candle you will NOT see much inside the egg but you may have a glimpse of yolk moving as you gently rotate lightly colored eggs.


Chicken Embryo Development, views from the Inside AND Out. *Graphic Photos**










  Porous Egg



TINY Sappy spots possibly due to Rough Shipment of EGGS






Day 11 candle funky air cells from shipped eggs.

BLOOD RINGS clearly visible on light polish eggs




Saddle Shaped Air cell, where it dips on two sides

BLOOD RINGS clearly visible on light polish eggs



Note the pictures below on day 10

The two on the right have “scrambled” contents from shipping













When you Candle on day 7 there should be some light blood vessels surrounding it and you may see the embryo move.  See above and below video. My favorite time to candle! Eggs that are clear should be re-candled at 10 days before tossing. If your not sure and it doesn’t smell leave it!  If your egg is colored or a brown egg, it is harder to see through the shell, you may want to wait a few days and try again. Or find a better candler.  You can see the large round yolk move inside the egg, this is NOT the embryo at day 7! Its just the yolk!


It IS ALIVE!!!! Video below day 7 Candle

 candle day 7 incubator detached air cells eggs hatching spreadsheet day 7 14 18 20 21 candle pip pipping sappy leaking bad









 DAY 14




It will begin to look pretty dark in there! Look for movement.

You should again see some good veining. 



THIS is a video of a CANDLE at DAY 14!















Candle day 18 is to determine growth, weigh, pencil mark air cell size and dispose bad eggs. It will look pretty dark and FULL in there! You may or may not see movement on this candle. Its ok if not, don’t panic! The chick may easily be resting! See how that air cell is beginning to dip more to one side and if you lay the egg down it will roll into the hatching position. I set my eggs with lowest dip in the aircell up. This position for hatching is good so the chick is able to turn into position and I can easily see my pips too! Day 18 laying horizontal for actual hatching helps a chick hatch 1-2 hours earlier.  I lay my eggs down LOWEST DIP of the AIRCELL UP! This is the normal and most likely hatching position and the chick will break through or Internally pip and externally pip in that probable area.  See the image below with the x, x being lowest dip in air cell and probably pip area/s.







  700700I I



Stop turning, Remove Turner and Raise Humidity to 65% - 70%

depending on what your air cells may still need

NOTE: It is now known that the different embryos communicate with each other by a series of clicking sounds,

the rate of clicking being the important feature. Ensuring the eggs on the hatching trays are in contact with each other facilitates

the synchronization of hatching where the eggs are incubated in a modern machine. This assists in reducing the time between when the first and last chicks hatch.



After Day 18 candle you will “LOCK DOWN” your eggs. Lower the temperature see suggest temps below and increase the humidity the last three days. STOP turning and the incubator stays closed, for the next three days while the chicks hatch!  If you’re having a hard time with humidity it is OK to open quickly to boost, add warm water or increase the size of the pan or add a wet sponge. NEVER ADJUST HUMIDITY BY cutting back airflow. VENTILATION is EXTREMELY important at this stage!


Researchers have found that lowering temperatures will prolong incubation,

HOWEVER it is favourable to do so at the end of incubation.  

Day 19 & 20 Temp Min 98.0 Max 98.5

Day 21 Temp Min 97 Max 98.0

for more information please refer here: 




on what that chick is doing in that egg at this time!

Development of motor patterns in avian embryos:

hatching behavior




CHICKS can get broken legs in these large sized wire grates

EXAMPLES Window SCREEN, or DOLLAR store rubber Shelf mat with the holes

see below:

Note:  foam grip drawer mat on the wire bottom of incubator on day on day 18 lockdown.  A cloth, crinoline, or paper towels could work as well. This ALSO protects the navel, the place where the abdomen closes after surrounding the remains of the yolk, from injury. It also makes cleaning the incubator easier. NO the wire on the incubator bottom should not injure or effect your chicks after they hatch.  Dollar store baskets are great to keep hatching chicks separated by breed.





Serama, Day 19 Draw down, very close internal pipping


another Serama Day 19 drawn down and very close to internal pip if its not already pipped




(shipped initially loose air cell, set after 12 hours and turned upright in the cabinet cooler incubator right from set)

Silky embryo in position for hatch and with internal pip (NOTE: NO EXTERNAL YET!) 



Note:  foam grip drawer mat on the wire bottom of incubator on day on day 18 lockdown.  A cloth, crinoline, or paper towels could work as well. This ALSO protects the navel, the place where the abdomen closes after surrounding the remains of the yolk, from injury. It also makes cleaning the incubator easier. NO the wire on the incubator bottom should not injure or effect your chicks after they hatch.  Dollar store baskets are great to keep hatching chicks separated by breed.







Prepare everything you need for them once they have hatched.

Now is the time to do final checks on brooder, heat lamp and feed. 

See bottom of article for links on chick care.  

Click on the link below for Brooder Ideas! 




Rocking Egg Video! 

Eggs can rock for several days before hatcing, but how exciting it is!






Understanding The Hatching Process


Between the 15th and 16th days, the chick orients itself so that its head is near the air cell at the large end of the egg. Not long before the chick is ready to attempt to make its way out of the shell its neck acquires a double bend so that its beak is under its right wing and pointed toward the air cell.


21 DAYS is just a baseline for hatching eggs.

Many chicks can take 23 - 25 days!

Some pip internally and fully hatch in hours while others will be 24 hours or more.


Egg movement! Eggs can “Rock n Roll” days before they are due to hatch!


The initiation of hatch occurs partially from the increased carbon dioxide level in the egg. This process causes the embryo to begin twitching it's muscles allowing the inner shell membrane to be punctured by the egg tooth. The chick then begins breathing the air in the air cell. Using its egg tooth, it pecks at the shell thousands of times and after a few hours the chick pips a small hole through the shell and begins to breathe air directly from the outside. After the chick has made a hole in the shell, it stops pipping for 8+ hours sometimes up to 24 hours and rests. During this time, it is acclimating its lungs.


700 700




In regards to opening and closing the bator to remove already hatch chicks; It is important to remember that chicks can go 3 days without food/water. It is better to wait for the remaining chicks to hatch to insure reducing the impact to unhatched pipping eggs.


But my new chick is running around in the bator knocking eggs around!








 MONDAY 5 PM noticed external pip




hole slightly larger but chick is NOT zipping!





missed the last quick zipping! 

Silky on the left, two CCL hatched at the same time!


THIS CHICK TOOK WELL OVER 24 hours to hatch! and absolutely normal!



Hatching egg shrink wrapped air cells incubator incubation





Oh NO!



It is common to lose about 1-2% of the chicks due to deformities and malpositions. Deformities occur during embryo development, while malpositions occur the last week of incubation. Malpositioned embryos are unable to pip the eggshell and escape due to improper positioning within the egg. The chicks can have difficulty positioning for pipping, absorbing the yolk sac, or changing from embryo to chick breathing air. The majority of malpositioned embryos that have died in the shell probably resulted from exhaustion and/or lack of oxygen. One GOOD thing to remember is that SOME malpositions are Lethal and some are not! Occasionally, malpositioned chicks will hatch unassisted but the hatch does need to be monitored closely to ensure that the chick is not becoming stressed, or stuck. Often as a result of the position in the shell they have been unable to absorb all of the yolk. Please refer to Navel SECTION BELOW.



Common reasons of Malpositions are:

Eggs are set with small end up.

Advancing breeder hen age and shell quality problems.

Egg turning frequency and angle are not adequate.

Inadequate % humidity loss of eggs in the setter.

Inadequate air cell development, improper temperature and humidity regulation, and insufficient ventilation in the incubator or hatcher.

Imbalanced feeds, elevated levels of mycotoxins, and vitamin and mineral deficiencies.

Lower than recommended temperatures in the last stage of incubation.

Normal hatching position and the six recognised malpositions Images:




CLICK here....







When to assist?

Assisting a chick should be your LAST RESORT


BEFORE you try to assist a chick!


Step By Step Guide

to Assisted Hatching:





She HATCHED! But what's with her butt?




If there is slight bleeding at the navel use corn starch or a dab of cold water to stop the bleeding. You can also swab the umbilicus area with a 1% solution of Betadine and place the chick back in the bator to dry. If you do see this and the chick is already out of the shell dangling with this, use a clean sterile scissors to cut through them, DO NOT PULL as you can harm the chick’s navel!

But only the cords!





Please see HOW TO TREAT & PREVENT yolk sack infections!!

click on in the link below

Mushy Chick Disease aka yolk sack infection & omphalitis


Below is a photo of a "Duck in a Cup" waiting for its yolk sack to finish up!




3 Essential Chick Care Tips (pasting up and Cord info)





YES this CHICK MADE IT through with proper Care!



And this one MADE IT! Say Hello to "Yolk"

Yolk, a WONDERFUL Story of a Chick that stopped pipping midway and ended up having a yolk sack rupture and a bunch of other issues! It is well worth a read and "Rock" has all the footage to boot!



700 700


Links for additional information



What Went Wrong During Incubation



Why break out and analyse hatch debris?

Procedure for breaking out hatch debris
Common MalPositions IMAGES
HOW to Analyze
Possible causes of Hatch Debris Embryo Mortality

High Humidity ~ cause  read page 36




Trouble Shooting Failures with Egg Incubation


 Hatchability Problem Analysis


Troubleshootting Incubation


This is also a great pdf with pics: paste link in browser search:


Eggtopsy: What happened to my egg?


"Shrink wrap" vs. "Sticky chick"?


Signs of Deficiency in the Embryo


• Chick yield (the weight of the chick at hatch as a percentage of egg setting 
weight) is a simple method of checking whether hatch timing and incubation parameters are correct.






New Chick Care Links and Info




How to Spot Problems of Newly Hatched Chicks


Reasons for chick malformations



GROW GEL / FEED Newly hatched chick! 

 WHY I always add little soda caps full of grow gel when my first chick is fluffed in the incubator.  

Does it do anything?  I thought they had the yolk!  

 Read PAGE 6

"The development of the gastrointestinal system is stunted under fasting conditions, and this may be related to the retarded utilization of the yolk (Dibner, 1999)"  





DIP THE BEAK OF THE CHICK IN THE WATER BEFORE YOU TURN IT LOOSE in the brooder. A taste of water right away helps them to find more water soon. If your chicks are at all stressed, add about 3 tablespoons of brown or table sugar to each quart of water for extra energy. Most baby bird loss is caused because the bird doesn't start to eat or drink. Never let your bird run out of water.


Homemade Electrolyte Recipe for weak/ill chicks
2 C. Water
2 TBL. Brown Sugar, honey or molasses
1/2 tsp Salt
1/2 tsp. Baking Soda

Mix until all dry ingredients dissolve & Keep refrigerated

You could also use electrolyte drinks Gatorade or Pedialyte, or

3 drops of POLYVISOL (liquid childrens A-B-D vitamins)

Slowly drip along inner edge of lower beak.

How To Raise Baby Chicks


 Raising your chicks


Dont forget to have Sav-A-Chick™ Electrolyte and Vitamin Supplement on hand! AND ITS CHEAP at TSC its Balanced electrolytes supplement for newly hatched and adult chickens, ducks, turkeys, and other domestic poultry. Fortified with vitamins A, D3, E, C, K, B1, B2, B3, B5, B6, B9 and B12. Convenient, single-use packets each mix into one gallon of drinking water. Use during hot weather or other stress to support optimal hydration and bird health. JUST IN CASE you have a weak bird! OR You can add sugar to the water in the first couple of days.

Free eBook: The My Pet Chicken Guide to Chicken Care



WRY NECK / Torticollis

Wry neck is a condition in which the baby chicks head or hangs it sideways or tilts backwards, causing it to be off balance and fall over. Sometimes chicks can be weak and fall over but if its tilting of head back is causing toppling its typically wry/crooked neck.


Torticollis is a symptom from different illnesses. Marek's disease, a possible vitamin deficiency in magnesium, vitamin E, thiamine, avian encephalomyelitis or listeriosis, food poisoning/botulism, heavy metal/lead toxicity, Fungal aspergillosis, ear infections, and head injuries with some vulted skull breeds.

Vitamin Deficiency-Induced Neurological Diseases of Poultry 

AWESOME links here! :

Vitamin E with Selenium, Water Soluble Multi Vitamins plyvisol NO IRON, Probiotics & Electrolytes, Prednisone,Bayer Brand Baby Aspirin

MASSAGE, Vit B, Vit E, Selenium

help them get out of their twist!








Vitamin Deficiencies in Backyard Chicks and Chickens






Chick in a babyfood container to help "bring legs" together



Curled Toes



Understanding Splayed Legs and incubation distress that easily leads to splayed legs

This condition has been associated with high humidity during incubation, but the results of our research indicate that higher temperature conditions during the last phase of embryo development may have a bigger impact. Splayed legs are also observed when newly hatched chicks are placed on slippery floors.



Culling ~

Small Animal Euthanasia at Home

How to cull chicks

How to Dispatch a Chicken.



Medicine Chart for Chickens & other Poultry


Sexing Chicks




Learn CPR: Save A Bird’s Life

CPR can save a bird’s life in the correct circumstances, so learn how to perform CPR on your bird with these tips.





SmallScale Poultry Flocks Resources

a PDF Filled with Informative links to EVERYTHING POULTRY!











A few Cool Videos!



THIS is a video of a CANDLE at DAY 10!



Day 13 Duck Candle below










Pip to chick!

Welcome Splash Silkie, Halo!


         pip incubator detached air cells eggs hatching spreadsheet day 7 14 18 20 21 candle pip pipping sappy leaking bad








Air Cell detatched 



Air Cell detatched







Everyone is MORE than WELCOME to come join the Incubation thread with us!

you can find us here...


 INCUBATING w/FRIENDS! come hatch, learn, Chat, Meet new Friends!


Just pop in and say hello and what your plans are in the bator!

Experienced Hatchers also needed to help out with the growing demand for help with incubating!

Its not just for shipped eggs! Its awesome, most check daily and are there to help and support!




Disclaimer: Please note this information is offered as friendly advice only and, whilst I have made every effort to ensure it is accurate, I can not be held responsible if it proves not to be useful in your case!


Sally Sunshine profile picture

Sally Sunshine






INCUBATING w/FRIENDS! come hatch, learn, Chat, Meet new Friends!


Hatching 101 Guide ~      Guide to ASSISTED Hatching ~


 Mushy Chick Disease  ~ Duckling Care ~  "Nasty CKN Butt"~ Fermented Feed! ~ Processing Support

Pallet COOP~ Saloon COOP~ EASY 5gal Waterer~ PINTEREST Chickens~Gettin the Flock out of hereCHICK LIGHT BOX 





Sally Sunshine Poultry






A little fun compliments of my friend Oz!









My new Avy Created by my friend cochins1088 from BYC,

How cool is that!












Comments (42)

thanks for all the info hope we end up getting to meet up one day can't wait to see if any of my silkies or frizzles make it
Beautiful chickens and Thanks for all the info Its fun and sad but it does help all of us .
Hey SS, I especially like the section on helping (or not helping) a chick to hatch. Very good reference!
Thanks SUMI for the thumbs up on the Article/Notes! Glad my notes can help others too!
Oh my, you are so smart for putting all of this together! I wish I had done something similar when I did so much research. Thank you for taking the time to do this and sharing! It should help so many on there. :)
Way to go!!! Best reference material that I have seen on hatching and incubating. Great job and thanks for putting it all together and sharing.
YES! Thank you so much! Awesome thread!
thanks for the info!
This is great !!!....thank you so much
Thank you Sally.You have always been helpful and have saved thousand of chicks :)
Keep it up we want more from you.
Thumbs up.... Thankyou for publishing such great information for those who are new to the incubation/hatching.
Great resource. Thank you!
Wow great article and thanks for all your hard work with so much information.
Superb information, you did a LOT of research putting this stuff together....the best I have ever seen. Good JOB!! If anyone has any question imaginable it can be answered in the links, etc awesome, love internet!
I'm a beginner, and this is chock full of good stuff!! Thank you sooo much!
Amazing thread! On behalf of newbies and experienced hatching peeps, I say Thank You Sally Sunshine. Wonderful Post!!!
Hydrometer Calibration
Place the salt in the bottle cap (or other small container).Dampen the salt with water. Do not put so much in that the salt gets "sloppy". You want a damp pile of salt in the bottle cap.Place both the hygrometer and the bottle cap full of damp salt in the ziploc bag and seal it well. (It is important not to let air on or out while the test is going on.)Keep it like this for over 8 hours.After 8 hours in the damp salt environment, the actual humidity inside the bag will be 75%. Compare it to your hygrometer, your hygrometer should also read 75%. If not, you will then know exactly how far off your hygrometer is. If it's off, note the amount and direction that it actually reads and be sure to add or subtract that amount when reading the hygrometer. If the hygrometer has a control to adjust it (either the needle or the display), you can set the hygrometer to 75% immediately after the test.
BackYard Chickens › Learning Center Articles › Hatching Eggs 101