Well in the large milk crates...4 can fit! Now while no one could move or possibly lay comfortably in those conditions, they did fit. I have two milk crates sitting upright with straw in them and this morning everyone wanted the two milk crates instead of the other nest boxes. So one crate at 2 BAs in it and a NHR trying to get in. The other one had 4 BAs in it and a SLW looking for an opening place to climb on in. Silly Silly chickens! I will have to try to get a pic of these antics.