Square footage. That's some touchy real estate. I think if we all had a choice we would have as much as we could possibly get our hands on. But for most of us that just isn't the case. If you have the space and the funds and are contemplating chickens or a new coop and run build it bigger then you think you will need. You will use the space. I wish we would have built our sweet coop double the size it is. Cause guess what? We want more clucks. We have been able to add a few each year and will be able to add a few more this year but then that's it. We'll be done with adding clucks to the space we have for them. You see it all hinges on the square footage. A bigger space for the clucks is always better. Our hens have a nice size run and spend most of their time there. Using the coop to lay eggs and sleep. We also give them time out of the run out in the back yard. Allowing us to have a few more clucks then if we kept them cooped up all the time. If the clucks will be spending all of their time inside the coop, then in my opinion it would be best to have a minimum of 4 to 5 sq ft per bird. But have a look at what 4 sq ft really looks like and you will see it's not much space at all - so more space is better. If you have an enclosed run space along with your coop then a minimum of 8 to 10 sq ft outside per each bird. But again that just isn't that much space and if you can go bigger then by all means do so. Taking into consideration your own unique location and situation for your clucks and how many you think you would like to have, key word being think, because once you have clucks you will inevitably want more. Rethink what size coop and run you can build or accommodate because this will determine the number of clucks you will be able to have.