Get the CFM from your room size or fixtures using Home Ventilating Institute guidance.
How it works
Rooms under 100 square feet use 1 CFM per square foot with a 50 CFM minimum. Larger rooms add 50 CFM for each toilet, shower and tub, and 100 CFM for a jetted tub.
Before you order
- Vent outside, never into an attic.
- Long or crimped duct runs reduce real airflow.
- A timer switch keeps the fan running long enough after a shower.
Common questions
Do I need a continuous fan?
A fan left running can be much smaller, about 20 CFM, and is an accepted alternative in many codes.
What does sones mean?
It is a loudness rating, and lower is quieter. Under 1 sone is quiet for a bath fan.