Bathroom Fan Calculator

A second fan may be needed.

Bathroom fan calculator. For example a 7 ft x 10 ft 2 1 m x 3 m bathroom has a floor area of 70 square feet 6 5 square meters. If the enclosed space is small a 50 cfm fan should suffice. A bath vent fan duct that is too short may violate the manufacturer s installation instructions may not work properly or may be drafty.

Here we provide specifications for recommended minimum maximum duct lengths for bathroom vent fans. Why you need to have the proper size extractor fan. Well managed indoor air quality is crucial to code compliance.

This fan calculator is typically used to calculate the cfm or cubic feet per minute of air exchange that may be desired in a building. Bathroom fan exhaust size calculator. When installing a vent fan make sure there s at least a 1 2 gap under the bathroom door to allow fresh air to enter the room when the fan is running.

The formula to calculate bathroom exhaust fan size reads as follows. The higher the bath fan rating the more air can be vented out of the bathroom which means less moisture and mold build up. A bath vent fan duct that is too long may restrict air flow such that the fan is not functional.

Whether exhausting air or bringing fresh air into a structure the calculation produced should help to figure out the size of fan s required to accomplish the air exchanges needed. Cubic volume 7 5 cfm necessary. Calculate the floor area of your bathroom.

For example if your bathroom is 80 square feet you ll need an 80 cfm fan such as the broan smartsense 80 cfm ventilation fan available from supplyhouse. Bathroom extractor fans are mandatory in any bathroom without a window and still highly recommended in bathroom with windows. Other options for bath fans include lights heaters and even humidity sensors.