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Basements · rooms · crawl spaces

Dehumidifier Size Calculator

What size dehumidifier do you need? Set the size of the space and how damp it gets. We give the capacity ENERGY STAR recommends and the models that cover your space.

sq ft
How damp is it without a dehumidifier?
Recommended capacity –pints/day
How we got this number

    100% private: the math runs in your browser and nothing is sent anywhere. Estimates for one room or open space up to 2,500 sq ft.

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    Dehumidifiers for your space

    Coverage and pints as stated by each manufacturer, checked October 2026. As an Amazon Associate, ComfortSizer earns from qualifying purchases.

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    How dehumidifier sizing works

    Dehumidifiers are rated in pints of water removed per day. ENERGY STAR recommends a capacity based on how damp the space is and whether it is under or over 2,000 sq ft, and it advises erring on the larger side.

    ConditionUp to 2,000 sq ftOver 2,000 sq ft
    Damp or musty (50–75% humidity)20–30 pints30+ pints
    Damp spots on walls or floor (75–90%)25–40 pints40+ pints
    Walls sweating, seeping water or drying laundry (90–100%)30–50 pints50+ pints

    The pint confusion: read the test condition

    In 2019 the U.S. Department of Energy changed the test for dehumidifier capacity to cooler, drier conditions (65 °F, 60% humidity). The same machine now gets a smaller number: Midea, for example, states that its 35-pint (2019) model equals 50 pints under the old test.

    Many listings still advertise pints measured at 95 °F and 90% humidity, which produces much bigger numbers. That is why each model on this page shows the condition its maker uses. Compare like with like, and treat a "50 pints at 95 °F" claim as a smaller machine than a "50 pints (2019 DOE)" one.

    Basements and crawl spaces

    Below-grade spaces are often cooler than 65 °F. Look for a model rated to run at low temperatures (auto-defrost), and use continuous drainage with a hose or a built-in pump so you are not emptying a bucket every day.

    FAQ

    Questions

    What size dehumidifier do I need for a basement?
    For a typical damp, musty basement under 2,000 sq ft, ENERGY STAR suggests 20 to 30 pints per day (2019 DOE rating). If you see damp spots on walls or floors, 25 to 40 pints; if walls sweat or water seeps in, 30 to 50.
    What size dehumidifier for 1,000 square feet?
    It depends on how damp the space is: 20–30 pints for a musty space, 25–40 with visible damp spots and 30–50 if walls sweat or you dry laundry there.
    Is a 50 pint dehumidifier too big?
    Rarely. ENERGY STAR advises that it is better to oversize than undersize. A larger unit reaches the target humidity faster and cycles off.
    What is the difference between 2019 DOE pints and old pints?
    The 2019 DOE test uses cooler, drier air, so capacity ratings dropped. A unit rated 35 pints under the 2019 test was sold as about 50 pints under the 2012 test.
    What humidity should a basement be?
    Keeping indoor humidity between about 30 and 50 percent helps prevent mold, musty odors and dust mites.