How to know which size bathroom fan to purchase for your main bathroom, powder room or ensuite bathroom.

How many CFM do I need for my bathroom fan?

Interior design Jil Sonia Interiors, Abbotsford, BC Photo by Ina van Tonder, Surrey, BC.

Wondering how to calculate which size of fan you need for your bathroom?  For a bathroom with a tub or shower, here's the magic ratio!

Calculate the volume of your bathroom:
Height of the room x length of room x width of the room = total volume.
ie. 8' high x 10' long x 6' wide room =  480 cubic feet.

Now divide the cubic feet by 7.5

480 divided by 7.5 = 64 cfm fan size.  Or select the closest available fan size, when in between sizes, always select the higher CFM fan.  Meaning, if there is a 50 CFM fan and a 75 CFM fan, select the 75 CFM fan.

There you go!