Dehumidifier capacity is the amount of water the appliance can remove in 24 hours under its test conditions. Enter the area and choose the description that best matches the room before dehumidification.
Dehumidifier size calculator
Match portable-dehumidifier capacity to the room area and the moisture conditions you can actually observe.
Capacity is rated in pints removed per 24 hours under specified test conditions. Persistent seepage or mold needs its moisture source fixed as well as dehumidification.
How the dehumidifier recommendation works
The result uses the current ENERGY STAR dehumidifier sizing table. ENERGY STAR groups portable units by small-to-medium spaces below 2,000 square feet and large spaces above 2,000 square feet, then increases capacity as conditions move from moderately damp to wet.
Capacity labels changed after the DOE test procedure moved to cooler, more realistic conditions. A current 30-pint unit may therefore replace an older model with a higher-looking rating. Compare products using the current test rating rather than an old box or review.
Choosing the dampness level
- Slightly to moderately damp: intermittent musty odor or roughly 50–75% relative humidity.
- Very damp: persistent damp smell or visible damp patches, roughly 75–90% RH.
- Wet: sweating walls or floors, seepage or other high moisture loads, roughly 90–100% RH.
A hygrometer helps describe current humidity, but moisture varies through the day. Laundry drying, open crawl spaces, groundwater and ventilation can all change the load.
Capacity is not the whole solution
Fix leaks, seepage and drainage problems where possible. Very cool rooms can make a refrigerant dehumidifier less effective; ENERGY STAR notes that frost can form on coils below about 65°F. See our guide if your dehumidifier keeps freezing up.
Frequently asked questions
Is it better to oversize a dehumidifier?
ENERGY STAR advises that oversizing is preferable to undersizing, but a correctly controlled unit is still important. Compare noise, low-temperature operation, drainage and integrated energy factor as well as capacity.
Does this size a whole-home dehumidifier?
No. Ducted whole-home equipment needs an HVAC assessment that considers infiltration, ventilation, climate, air-conditioning operation and the building envelope.