How to Size Bathroom Fans

Bathroom fans are more important that other rooms because bathrooms are subject to high air temperatures and humidity levels. These factors are detrimental to wooden doors because they cause them to warp, and can also cause paint damage. To prevent this, install a fan in your bathroom that can change the air at least eight times per hour. The size of a bathroom fan is measured in cubic feet per minute.

Things You'll Need

• Measuring tape

Instructions

1. Measure the length, width and height of your bathroom by using a measuring tape. Be sure to measure in feet.

2. Determine the volume of your bathroom by multiplying the three dimensions. For example, if the length is 12 feet, the width is 9 feet and the height is 8 feet, the volume is 864 cubic feet.

3. Divide your volume by 7.5, the number of minutes per air change, assuming eight air changes per hour. This will give you the minimum cubic feet per minute your bathroom fan needs. For example, a bathroom with a volume of 864 cubic feet would need a fan capable of at least 115.2 cubic feet per minute.

References

• Bathroom Exhaust Fan Information
• Bathroom Fan Sizing