For example if your bathroom is 80.
Exhaust fan size for toilet.
If the enclosed space is small a 50 cfm fan should suffice.
To arrive at your required cfm simply divide your bathroom s volume by 7 5.
An effective bathroom fan should be capable of replacing the entire volume of air 8 times per hour or every 7 5 minutes.
For example a bathroom with a volume of 1000 cubic feet 28 3 cubic meters needs a fan capable of moving 1000 7 5 or 133 cfm 3 8 cubic meters per minute.
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.
Otherwise use the appropriate calculation based on the room size.
The vent material smooth vs.
The formula to calculate bathroom exhaust fan size reads as follows.
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.
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.
A second fan may be needed.
Because toilets are usually in small rooms a small quiet exhaust fan should do the trick.
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 fan is described as a sanity saver by homeowners fed up with noisy bathroom exhaust fans.
Just remember that the fan needs airflow to do its job.
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.
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.
Of course this depends on your circumstances so we recommend using our simple exhaust fan calculator to decide which fan you need.
Cubic volume 7 5 cfm necessary.
10ft 10ft 8ft 7 5 106 67 cfm.
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.
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.
How to choose one.
But o brian suggests a simpler rule of thumb.
A diameter of 4 inches is common for exhaust ducts but some high cfm fans fit a 6 inch diameter duct.
With a power level of 70 cubic feet per minute cfm this fan will handle bathrooms up to 70 square feet in size.
Bathroom fan exhaust size calculator.
Here s how we get this number.