I do use less per chicken than the generally recommended 4 sq. feet per bird...but I also have a huge run/sq. feet per bird, PLUS a good amount of covered (i.e. solid roof/out of elements) space outside of the coop for them. That said - especially in warmer climates ( yours is considerable warmer than mine, in general), you will want more coop and more roost space per bird so they are somewhat comfortable in the summer at night. While I have less formal coop space, half of my raised coops as 'proper coop', the other half I can walk in, is still very safe, but not solid walls all around - hardware cloth plus partial walls with a roost in the back half - so in 'nicer weather' they have additional safe, solid roof nighttime roosting space so they can spread out and be more comfortable in the heat, but still be out of the rain and, if needed, can also put up my specially erected tarp to keep them out of the wind (if needed), So, this increases their roosting space by 50% that is usable for up to 7-8 months of the year - which they GREATLY appreciate in warmer/muggier weather. (plus, another diagonal roost under the coop that is 5+ feet long, but I consider it to be about 4' more of roosting space due to meeting wire 'walls' on the diagonal - this actually doubles their evening roosting space, and actually gives them about 5 sq. feet per bird in hot weather for night-time space)
Please don't skimp on roost space/coop space, particularly for warmer months. Trust me, your girls will appreciate it. They don't mind snuggling in the bitter cold, but they really appreciate the 'elbow room' in warmer weather.
I've included a rough sketch of my 'coop' so you can see what I mean. Hopefully my attempt at sketching is good enough for you to understand my coop set-up. All of the permanent coops I have designed/built ( except for my broody/mating/injured 'coop' which is at ground level with roosts above that everyone can access (and is under a solid roof). My mobile coops are completely different - but that is another story.
I hope that this helps, and that you really do give both coop space and roost space some real consideration - if there isn't enough coop space, it can cause a fair amount of stress and lead to some bad behaviors - especially if you have multiple roosters - but certainly with the hens, also.
(Sorry, it can be hard to read this part because it got partially cut off. This particular coop - the 'base' is 4' X 8' ( so 32 sq. feet), the coop proper is 4'x4' (16 sq. feet) All of the space is completely safe with the 'open air' part enclosed in 1/2" X 1/2" hardware cloth with 2X3" welded wire underneath the hardware cloth for extra reinforcement - and 2X3" welded wire under the base in addition to perimeter protection. The coop proper is solid plywood except for venting areas, which are, again, 1/2 X 1/2 hardware cloth. It opens into the run - the back side of the coop is part of the 'run wall'. Under the coop is protected from elements, and the pop door opens to a 18' X 24" 'safe run, that has 24'X10' with solid roof, the rest of the run top is open to the elements. This 'run' is inside of my 'extended run' that doesn't at present have any hawk protection(but will soon, when it gets expanded this spring), that is 50' X 25', soon to be 50' X 30' - again, with soon top protection as well. There are additional coops that also are elevated that give additional protected space from elements, in addition to the 32 sq. foot coop shown here and the 'attached 180 sq. feet of solid roof run.
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Note that despite my 1250 sq. feet of run space (plus coop space ), I think it is not enough for my birds -so I only have approx. 60 birds in there. I have the rest in 2 other runs ( about 95 total birds after extra young roos and a few older hens were processed) My other 26 birds - 2 groups of 13 - have almost, but not quite, as much space per bird as there. And all get to free range some most days - even if it is only an hour per day on weekdays, and more most weekend days.
They don't have the space
@RoyalChick 's birds, do - but I do want them to have enough space to be healthy, happy, and be able to do chickeny things.