Chicken Coop For 16-20 Chickens - Doing the Math
Most chicken coop dimensions are shown in inches, rather than feet, so in order to get the area of a chicken coop in feet, you are first going to need to divide the number of inches for each dimension by 12 before multiplying the length times the width to get a coop's square footage. For example, a 90" x 78" chicken coop is 7.5' x 6.5', or 48.75 square feet. Depending whether you use 2, 3 or 4 feet per bird, that size coop could comfortably house 12-24 standard size chickens.
Unfortunately, not every chicken coop manufacturer is entirely accurate in stating the number of chickens it can hold (let's just give them the benefit of the doubt and say that they are really bad at math). So, please do your own calculations before deciding which coop is best for your flock of 16-20 chickens.
Also, be sure to factor in the amount of roost space a coop has in addition to its number of nest boxes and whether or not it also has a chicken run attached to it. All of those things can limit or expand the number of chickens a coop can accommodate. For much more detailed information, please be sure to visit our buyer's guide article, What is the Best Chicken Coop for Me to Buy.