Appliances & Utilities calculator
What Bathroom Extractor Fan Size Do I Need?
Use bathroom volume, target air changes/hour, duct loss factor to find bathroom extractor airflow.
Enter your measurements
What Bathroom Extractor Fan Size Do I Need uses bathroom volume, target air changes/hour, duct loss factor and the other configured measurements to return bathroom extractor airflow with a formula written specifically for this tool.
- Bathroom volume — Required
- Target air changes/hour — Required
- Duct loss factor — Required
Bathroom extractor airflow
Enter the measurements above to calculate bathroom extractor airflow.
How the calculation works
V17 calculation: requiredFlow=bathroomVolume×targetAirChanges×ductLossFactor/3600. The result is reported as Bathroom extractor airflow.
Worked example
Example: Bathroom volume = 15000 L; Target air changes/hour = 6; Duct loss factor = 1.2. Result: Required Flow = 30 L/s.
Before you decide
The result is only as accurate as the measurements entered. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what bathroom extractor fan size do i need, the limiting result on this page is bathroom extractor airflow.
Direct measurement/geometry calculation. No external reference is required for the arithmetic itself; the result is derived only from the user-entered measurements and the formula stored in calculationLogicJson.
Frequently asked questions
What does the Bathroom Extractor Fan Size calculator tell me?
It returns bathroom extractor airflow from the measurements entered on this page. The calculation is specific to bathroom extractor fan size, so the result should be compared with the exact product or specification you are considering.
Which measurements should I take for bathroom extractor fan size?
Measure bathroom volume, target air changes/hour, duct loss factor. Use clear, usable dimensions rather than nominal room or product labels.
Should I round the bathroom extractor airflow?
Keep the calculated value for comparison, then choose a real product that meets or stays within the returned bathroom extractor airflow while allowing for the clearances, tolerances or ratings shown by its manufacturer.