For bathrooms less than 100 square feet you can just go with 1 cfm for every square foot of floor area he says.
Exhaust fan size for toilet.
A second fan may be needed.
A diameter of 4 inches is common for exhaust ducts but some high cfm fans fit a 6 inch diameter duct.
This fan is described as a sanity saver by homeowners fed up with noisy bathroom exhaust fans.
If your bathroom has a toilet or shower area enclosed by a door it s a good idea to install a separate exhaust fan for that area.
Of course this depends on your circumstances so we recommend using our simple exhaust fan calculator to decide which fan you need.
How to choose one.
The vent material smooth vs.
The fan model its size and cfm rating or the required or design flow rate in cfm from your local code such as 60 or 80 cfm.
Why you need to have the proper size extractor fan.
The formula to calculate bathroom exhaust fan size reads as follows.
For example if your bathroom is 80.
All you need to do is select the application from the dropdown enter the size of the room and we will provide you with a general capacity range m3 hr that you should be looking to achieve from the extraction fan.
Otherwise use the appropriate calculation based on the room size.
The room s size measured in m3 is the most important factor to determine which exhaust fan is suitable for your toilet.
Bathroom fan exhaust size calculator.
If the enclosed space is small a 50 cfm fan should suffice.
The calculator on this page is provided as a general guide designed to help you select an exhaust fan which may be suitable for your needs.
You can upgrade to a larger diameter duct for greater efficiency or you can use an adapter reducer often included with the fan to fit the smaller duct.
Industry experts recommend 60 cfm to 80 cfm for small bathrooms and 200 to 300 cfm for a large bathroom with a steam generator.
This page is designed to be a general guide for selecting an exhaust fan based on the size of the room and the type of application the fan will be used for.
Just remember that the fan needs airflow to do its job.
10ft 10ft 8ft 7 5 106 67 cfm.
To arrive at your required cfm simply divide your bathroom s volume by 7 5.
Here s how we get this number.
Because toilets are usually in small rooms a small quiet exhaust fan should do the trick.
Cubic volume 7 5 cfm necessary.
By simply inputting into the calculator the dimensions of your room and the type of room application for the fan the calculator will provide you with a suggested general capacity range in cubic metres per hour m3 hr to help narrow down your exhaust.
Determine the required cfm for your bathroom fan.
With a power level of 70 cubic feet per minute cfm this fan will handle bathrooms up to 70 square feet in size.