I have a bathroom fan that died recently. It is a basic Broan from the 90's, 50CFM and 2.0 sones.
I want a quieter fan for sure, but I'm not sure on the sizing. As shown in the picture, our bathroom (shower, tub, toilet) area (green) is 50 square feet, but our vanities are in an adjacent room (blue) that is 30 square feet. Both have standard 8' ceilings. Our master bedroom is next to that. We almost never close any of the pocket doors between the rooms, unless we are getting ready when the other of us is asleep.
So, do I need to account for the additional area when calculating CFM? Accounting for the short duct to the roof cap (~35' EDL, I think we have 4" duct) that puts me at either 60 or 90 CFM according to this chart:
So, I guess the question is, does it matter that much? 50, 60, or 90 CFM? (or 110??). Our bathroom tends to stay humid for a while currently, but I'm not sure our fan has been running at full capacity either.