Rules of Thumb
- If it looks like a dollhouse it's only suitable for toy chickens.
- If it's measured in inches instead of feet it's too small.
- If your walk-in closet is larger than the coop-run combo you're thinking of buying think carefully about whether you have an utterly awesome closet or are looking at a seriously undersized chicken coop.
- If a man of average height can't lie down in the run and stretch out comfortably it's too small.
- If it has more nestboxes than the number of chickens it can legitimately hold the designer knew nothing about chickens' actual needs and it probably has other design flaws too.
These numbers are guidelines, not hard and fast rules, but they're a good place to start when looking at plans. Don't even think about the numbers the coop claims to hold, get the dimensions and do the math.
The Usual Guidelines
For each adult, standard-sized hen you need:
- 4 square feet in the coop (.37 square meters)
- 10 square feet in the run (.93 square meters),
- 1 linear foot of roost (.3 meters),
- 1/4 of a nest box,
- And 1 square foot (.09 square meters) of permanent, 24/7/365 ventilation, preferably located over the birds' heads when they're sitting on the roost.
6 hens
- 24 square feet in the coop. 4'x6' is the only really practical build for this given the common dimensions of lumber. If you can't walk into it, put the access door in the middle of the long side to make sure you can reach all areas of the coop because a stubborn chicken WILL press itself into/lay an egg in the back corner where you can't reach.
- 6 feet of roost
- 60 square feet in the run. 6'x10' or 8'x8'.
- 6 square feet of ventilation.
- 2 nest boxes, to give the hens a choice
But since 6 is a "start with" number,
12 hens
- 48 square feet in the coop. 6'x8' is more practical than 4'x12' since a long, skinny coop like that would be difficult to work inside.
- 12 feet of roost
- 120 square feet in the run. 10'x12' or 8'x15' -- 8'x16' means fewer odd cuts than either of those. 6'x20' is possible, especially if your run is an open-topped, fenced area instead of fully-enclosed with a solid and/or wire roof but risks social problems because subordinate hens need to be able to pass the dominant hens at a respectful distance.
- 12 square feet of ventilation.
- 3 nest boxes.
Diagonal roosts, like excessive nestboxes, are a tip-off that the designer didn't know anything about chickens' real needs. While they appeal to humans' sense of aesthetics and efficiency, they are not good for chickens because they won't roost on the ends where their tails get mashed against the walls so only the portion of the roost that's at least 10-12" from the wall counts.
Additionally, chickens fly at about a 45-degree angle and they need space to fly up to and down from the roosts. that means that there needs to be a distance at least the same as the roost height from the wall opposite so that they don't crash.
