Coop question

I got a nice 10x12 shed that I was going to convert into a coop
but my husband is in love with it and wants to use for an actual shed

My question, unsure the amt of chickens right now, we HAD 20 ish before they got eaten
1)if the chickens free range what size coop would I have to have
2)if they had an 8x55ft run, what size coop would I have to have

I know the rule of thumb is 4 sq ft per bird but I read that if they have enough outdoor space, I could fit more birds in the coop? I'm not sure I'm remembering that correctly

These tables for chickens, from heat recommendations for chicks to square footage for keeping adult chickens, are really over-simplified, and they don't really address the specific, real-life needs.

For coop space, you need more than minimum square footage of floor space. You need adequate perch space that enables chickens to have room enough to flap their wings to lift their bodies up to roost without knocking off other chickens in the process. Therefore, the recommended one foot of perch length for each chicken is, realistically, less than what is actually needed. I would double it.

Other than that, if your chickens will be using the coop only for sleeping and laying, it doesn't need to be huge, but you need to make sure that there's room for the chickens to leap down from the perch without creaming themselves against a wall opposite it. If you have a perch running the length of a narrow coop, it should be at least four feet from the opposite wall to handle landings, and the perch will be, by necessity, at least a foot from the wall behind it, so your coop will need to be five feet wide minimum.

You won't need space for food and water, since they'll be outside most of the day, but you will need at least one nest box for every five hens, minimum.

So, those are the realistic specifications for chickens' needs. Now you can design your coop accordingly.