When buying off the shelf, don’t rely on the maximum number. For example, if there are coops that are advertised with a capacity of 4-6 hens, 4 is more likely a realistic number than the latter.
A lot of times, homeowners tend to miscalculate the number of chickens they want and end up buying a small coop. A little extra space never hurts. So always buy a coop that can accommodate a few extra chicken than what your current flock size is. This way, you can always expand your flock if need be. Provided you have enough room in your lawn to accommodate the coop and aren’t restricted by city ordinances.