Find the right dehumidifier capacity for a basement, bedroom or crawlspace. Enter the area and how damp the space is, tick any conditions that add moisture, and get the capacity in pints per day under both the older (pre-2019) ratings and the current DOE test standard that newer product labels use.
Last updated:
Space
Enter the area as
Extra moisture (each adds about 5 pints/day)
Enter your values to see the result.
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How to use the Dehumidifier Size Calculator
Enter the area to dehumidify, or its length and width, in feet or meters.
Pick the condition that best describes the space: a musty smell, damp walls, sweating surfaces or standing water.
Tick any extra moisture sources such as a humid climate or a washer and dryer in the space.
Read the recommended capacity. Use the 'new DOE' number when shopping for units sold since 2019 and the 'old rating' number for older models or older buying guides.
Dehumidifier sizing chart (old rating, pints per day)
This is the widely used industry sizing chart, based on the older test at 80 °F and 60% relative humidity. Add about 5 pints per day for each extra moisture source (humid climate, laundry in the space, several occupants, many doors and windows).
Condition
500 sq ft
1,000 sq ft
1,500 sq ft
2,000 sq ft
2,500 sq ft
Moderately damp
10
14
18
22
26
Very damp
12
17
22
27
32
Wet
14
20
26
32
38
Extremely wet
16
23
30
37
44
Areas between the columns are interpolated; larger areas are extrapolated at the same rate per 500 sq ft.
Old vs new (2019 DOE) pint ratings
Since June 2019 US dehumidifiers are rated at 65 °F and 60% RH instead of 80 °F and 60% RH. Cooler air holds less water, so the same unit's rated capacity drops by roughly 25%–30%. This calculator multiplies the old figure by about 0.71.
Old rating (pre-2019)
Typical new DOE rating
Liters/day (new)
30 pints
~20–22 pints
~10
50 pints
~35 pints
~17
70 pints
~50 pints
~24
1 US pint = 0.473 liters. Some manufacturers outside the US rate capacity at 30 °C and 80% RH, which gives much higher numbers for the same machine, so compare units only under the same test conditions.
Frequently asked questions
What size dehumidifier do I need?
It depends on the area and how damp it is. Under the older industry sizing chart, a 1,000 sq ft space that is moderately damp needs about 14 pints per day, a very damp one 17, a wet one 20 and an extremely wet one 23. Larger or wetter spaces need more. Add about 5 pints per day for extra moisture sources such as a humid climate or laundry in the room.
Why did dehumidifier pint ratings change?
In 2019 the US Department of Energy changed the test conditions from 80 °F and 60% relative humidity to 65 °F and 60%, which better reflects cool basements. Air at 65 °F holds less moisture, so the same machine removes fewer pints in the test. A unit once sold as 70 pints is now typically labeled about 50 pints, and a former 50 pint model about 35 pints.
Is it better to buy a bigger dehumidifier?
A somewhat larger unit is usually fine: it reaches the target humidity faster and runs fewer hours. A unit that is too small may run constantly without ever getting the space dry. Very large units in small rooms simply cycle more and cost more up front.
What humidity level should I aim for?
Indoor relative humidity between about 30% and 50% is generally recommended, and keeping it below 60% helps limit mold and dust mites. A dehumidifier with a built-in humidistat, or a cheap hygrometer, lets you check.
How do I describe how damp my space is?
Moderately damp: the space feels damp and smells musty only in humid weather. Very damp: it always feels damp, smells musty and has damp spots on walls or floor. Wet: walls or floor sweat, or moisture seeps in. Extremely wet: wet floors, standing water, or laundry drying in the space.
Does a dehumidifier work in a cold basement or crawlspace?
Standard refrigerant units lose capacity below about 65 °F and may frost up below roughly 41 °F. For cold spaces choose a model rated for low temperatures with automatic defrost, or a desiccant dehumidifier.
Is anything I enter sent to a server?
No. The calculator runs entirely in your browser.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.