The RIGHT humidity by successful long time hatchers


7 Years
Mar 30, 2012
SE Missouri
The Learing Center on BYC says humidity should be 50% for the first 18 days of hatching.

I have read others say 40-50% yet on the hatching forum here i read a lot of ppl have their bator set at 20-30% humidity

My bator directions said to error on the side of less but doesnt give a % only says "the air sack size etc" and then says you have to be experienced to read air sack and egg weight loss of weigh or gain correctly...

The lady i bought my eggs from who raises chickens says 50% .
I am confused...
SO..Any long time hatchers out there with a lot of experience ...PLEASE...what is the RIGHT humidity the first 18 day to get the biggest hatch success?
ONLY long timers in successful hatching please. ..
From what I've learned, there is no "right" humidity. You just have to use what you think will work best for you. Believe me, if you ask 10 different people they will all give you 10 different answers on what humidity is "right".

Just my two cents worth. Good Luck!
It is correct in saying "Believe me, if you ask 10 different people they will all give you 10 different answers on what humidity is "right" as Sunny said.

The right humidity is what works for you and your incubator.

My last two hatch's were great ones - 100% on the first and 90% on the second and both with totally different humidity levels for the first 18 days.

I averaged 45% on the first hatch and 32% on the second then for lockdown both humidity levels were at 60-65%.

So it is hard to say what is right and what is wrong when both worked!!
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i have a brinsea incubator and i beleive its all doen to ambiant air around you as well as the model incubator

Brinsea themselves say 45-55% first 18 days then 65% for lockdown

i have found to get correct 13% Egg weight loss i need mine set at 40% and 65% for lockdown is perfect

so yes it all depends on many factors

the way i found my optimal factor was to to everything i could on my first hatch

i weighed egg, looked at aircell, observed hatch, examines membraine after hatch everything basically

and from there i knew what was my best

i tried 45% incubation and 70-75% lockdown [was too wet]
40% Incubation and 65% Lockdown was perfect for me

one thing to remeber is when the chick makes that lasy push humidiy rises by 10% due to the chick being soo wet, i use that time to remove the shell as the inside of the shell is wet and makes humidity rise further and also that helps to bring back down the humidity to 65% [yes people say dont open in lockdown but for me opening for that split second to take out shell helps the chick with room to move and brings that high humidity back down again]

Try and see what you think is best
Thanks so much all.It is so helpful.
I am so green...I wish i hadnt started with some eggs i really want to hatch and get a chick or 2.
Dont want to ruin these Lavender orp eggs. Just couldnt wait and i didnt realize at the time there was so much to getting a chick from a egg even if you have a batch..My fingers are crossed for one anyway if i am REAL lucky..
Here's an interesting explanation of humidity: and why the optimal level can vary so much from incubator to incubator.

He has done a good job of explaining the complexities and it can be complex if you're determined to do the best possible job.

For those of us at or near sea-level and in a moderate (as in not really, really dry or really, really humid) climate then keeping the initial humidity around 40% with the final three day humidity between 60-65% should get you on the paper so to speak. You can then tweak it higher or lower from there once you have seen the results of the previous hatch.

There is no perfect humidity level for all the reasons that CM outlines.
Here's an interesting explanation of humidity: and why the optimal level can vary so much from incubator to incubator.

That is a very good explanation. Where I live I incubate between 35% and 40% humidity. When I go into lockdown I increase it to around 70% to 75%. I played with the humidity and this give me the best hatch rates. I have had 100% hatches.
Hummm very interesting link.
i have a fan which i believe draws air thru one of the vent holes as i think i mounted it over one. Wonder what type air exchange its giving me?
. I try and keep the humidity at 43-49 but at night it goes to 23 or so sometimes. but not always I dont understand why .I wil fill it at bedtime to about 43-45 humidity I have the other vent hole covered up. Now it is very humid here but i have the air on so that makes the air more dry.If your humidity is 40ish and yo uhave 100% hatch rate. Maybe iwill have a decent hatch (2 or more?) as Florida is humid too. and you use air conditioning i assume?Well i guess i have to wait and see.
Thaks very much to all

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