I read and read, searched some more and read some more about the coops on this site. It seemed that a standard coop door size is about 10 inches wide and about 12 inches high. My chicks were looking normal size and tad smaller than my aruacana chick. How much bigger can my brahma get?? Didn't think much when I started to build my coop. And now that the coop is nearly finished, I look at my light brahma. She's very pretty! At 6 weeks old, she stands over 10 inches tall and overtook my aruacana chick. So I read more about brahmas. Oh dear... descriptions uses things like "gentle giant", "size: heavy or very large". So searched using "brahma and chicken door" as the key words. Typical size door is about 12 inches by 18 inches which is quite a bit bigger than 10x12. I don't think 10 x 12 door is going to be large enough. It's better to fix things before I move my chicken into the coop. Also raising the bottom of the door off the coop floor by 3 inches. It was flush with the floor. Just when I thought I was finished... Well I guess my coop still isn't finished. I just want to finish the coop!! I just needed to vent!! Thank you all. We painted the coop in pretty pink. Girls you know... The coop has linoleum floor and linolium on the inside wall Picture or two will be posted when I finish the coop. It's taken me a really long time to build.