I'd have gone that big if we had the space. Wound up with 8 x 8 coop and about 450 square feet of run. A little tighter than I would like for 21 chickens. I only ordered 15, but 21 was the number that showed up and we're looking like maybe 100% pullets. Good news is they will have full time access to the run. I'm also going to build several structures to go inside the run so they can climb, look out, distance themselves from one another, etc. Really not an ideal real estate ratio, but I think they'll be okay.