Appliances & Utilities calculator
What Humidifier Size Do I Need?
Use room volume, desired rh increase, water needed per volume per rh change to find humidifier output capacity.
Enter your measurements
What Humidifier Size Do I Need uses room volume, desired rh increase, water needed per volume per rh change and the other configured measurements to return humidifier output capacity with a formula written specifically for this tool.
- Room volume — Required
- Desired RH increase — Required
- Water needed per volume per RH change — Required
Humidifier output capacity
Enter the measurements above to calculate humidifier output capacity.
How the calculation works
V9 calculation: requiredWaterOutput=roomVolume×targetHumidityIncrease×airMoistureCoefficient. The result is reported as humidifier output capacity.
Worked example
Example: Room volume = 45000 L; Desired RH increase = 20%; Water needed per volume per RH change = 0.2 L/day per m³ per RH fraction. Result: Required Water Output = 1.8 L/day.
Before you decide
Use the finished, usable dimensions after trim, handles, skirting, packaging or other projections where relevant. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what humidifier size do i need, the limiting result on this page is humidifier output capacity.
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 Humidifier Size calculator tell me?
It returns humidifier output capacity from the measurements entered on this page. The calculation is specific to humidifier size, so the result should be compared with the exact product or specification you are considering.
Which measurements should I take for humidifier size?
Measure room volume, desired rh increase, water needed per volume per rh change. Use clear, usable dimensions rather than nominal room or product labels.
Should I round the humidifier output capacity?
Keep the calculated value for comparison, then choose a real product that meets or stays within the returned humidifier output capacity while allowing for the clearances, tolerances or ratings shown by its manufacturer.