3 months old... About when do they reach full size?

[arizona_chicken_noob]

I am totally new to chickens and my Dominiques are 3 months old now. I'm wondering, about when are they full grown and/or how large should I expect them to be? I know that Dominiques are slightly smaller than other breeds, and I know "five pounds" is a weight estimate, but I am clueless to the volume of space each one will take up.

They look about the size of an American football at times, but there's floof going on. They feel about the size of a large pigeon.

Part of me is asking because I build a chicken pop door to the outdoor run and just wasn't sure if 10" (which the internet said is plenty) was realistic. I can always retrofit the door though if they outgrow it.

Thanks! Also, here's some chicken tax

 

[LadiesAndJane]

Most chickens reach full size by about 5 months of age.

 

[Ridgerunner]

Different chickens grow and mature at different rates. They do continue to grow for a year or more, but the major fast growth is usually over by 5 to 6 months. Don't expect a lot of real growth after that with your Dominiques. After that I'd call it more of thickening up. So if you have bands or rings on their legs to identify them you need to keep checking to make sure the band doesn't get too tight.

I've had full sized hens use an opening to the nest 6" high and 8" wide. Your 10" pop door should work well. As you've noticed they are mostly feathers as far as size, they can get through some small places.