How To Size A Bathroom Fan

When it comes to bathroom fans, size does matter. The right size fan will help to keep your bathroom free of moisture and odors, while also preventing mold and mildew growth. But how do you know what size fan you need? Here are a few things to consider:

Calculate the Cubic Feet of Your Bathroom

The first step is to calculate the cubic feet of your bathroom. To do this, multiply the length of your bathroom by the width by the height. For example, if your bathroom is 10 feet long, 8 feet wide, and 8 feet high, the cubic footage would be 640 cubic feet.

Determine the Air Changes per Hour (ACH)

The ACH is a measure of how many times the air in your bathroom should be exchanged per hour. For bathrooms, the ACH is typically between 5 and 8. So, for a bathroom with 640 cubic feet, you would need a fan that can exchange 5 * 640 = 3,200 cubic feet of air per hour, or 8 * 640 = 5,120 cubic feet of air per hour.

Choose a Fan with the Right CFM

The CFM (cubic feet per minute) is a measure of how much air a fan can move. To determine the CFM you need, divide the cubic footage of your bathroom by the ACH. For example, for a bathroom with 640 cubic feet and an ACH of 8, you would need a fan with a CFM of 5,120 / 60 = 85 CFM.

Consider Other Factors

In addition to the cubic footage of your bathroom and the ACH, there are a few other factors to consider when choosing a bathroom fan. These include:

The number of people who use the bathroom
The size of the shower or bathtub
The presence of any windows or other sources of ventilation

Conclusion

By considering all of these factors, you can choose the right size bathroom fan for your needs. A properly sized fan will help to keep your bathroom free of moisture and odors, while also preventing mold and mildew growth.