The general recommendations are as follows according to what I have read repeatedly on BYC:
4 square feet per chicken in the coop (minimum) plus 10 square feet per chicken in the run.
If all you have is a coop, and no run, then you would have to add those amounts together to be 14 square feet per chicken, IMO.
You have 48 square feet total, which will be their entire living space, correct?
If you ALSO have a run, then all you need to consider is the 4 square feet per chicken. These are general recommendations based on preventing cannibalism and feather eating.
So, if their entire living space is the 48 square feet, I would not put more than 3 hens in there. If that is just the coop, and you are providing an additional run, then you could easily fit 9 hens in there. You want at least one foot of roost per hen for comfort, IMO (unless they are bantams).