Phew - thanks!Yes, that should be enough space for 4 hens that are used to being together.
You may find this thread worth reading... https://www.backyardchickens.com/threads/ventilation-on-amish-style-coop.1449221/
I took a peek at the ventilation thread you suggested. The top of the coop is open (covered in hardware cloth), with a solid roof at an angle above that. Would the space between the solid roof and the header on the coop be how I'd calculate our ventilation sf? Initially, I was just thinking that it would be 3x5', which seems more than adequate for 4, but I guess not all of that translates to air flow if it can't go directly out.
For our area, winter temps range from 40-60F night/day, with a few nights close/at 32 F, and summer, 60-75, with a few days around 80 and a few 90-105. This is in a relatively shady part of our yard, though there's more shade in winter than in summer.