A 50 square foot or smaller bathroom needs a 50 cfm fan.
Cfm for bath fan.
An effective bathroom fan should be capable of replacing the entire volume of air 8 times per hour or every 7 5 minutes.
Suggested cfm for the bathroom is based on cycling all the air in the bathroom 8 times per hour.
Enter bathroom width ft.
Bathroom vent fans are rated for the amount of air they can move measured in cubic feet per minute or cfm.
The cfm represents the airflow required to completely exchange the air in your bathroom 8 times in one hour.
Bathroom vent fans serve an important function by removing humid air from your home to prevent mold and mildew from forming.
Enter bathroom height step 4.
Determine the required cfm for your bathroom fan.
Standard fan sizing applies to bathrooms that are 100 square feet or less.
In general for rooms with 8 foot ceilings.
Standard fan sizing.
Press calculate minimum suggested bath fan cfm.
For example a bathroom with a volume of 1000 cubic feet 28 3 cubic meters needs a fan capable.
So if you have a bathroom that is 12 feet long 15 feet wide and 10 feet tall then it has a volume of 1800 cubic feet 12 x 15 x 10 and a cfm of 240.
For bathrooms between 50 and 100 square feet estimate approximately 1 cfm per square foot.
A fan that s too small won t remove moisture and odors efficiently and will need to run longer increasing wear on the motor.
Enter bathroom length ft.
The rule of thumb is that you need at least 1 cfm per square foot of room area.
Vent fans are rated by the number of cubic feet of air they move per minute cfm and it s important to buy a large enough fan for the size of your bathroom.