Dehumidifier size calculator

Enter the size of the room or basement and how damp it is. You get the capacity to look for on a dehumidifier sold today, plus the older rating you will still see on charts and used units.

Free, no sign-up. Updated October 15, 2026.

Recommended capacity

12 pints/day

On the current DOE rating, the number on units sold since 2019.

17 pints/day on the older AHAM rating

Sized for up to 1,000 sq ft.

A starting point, not a guarantee. Cool basements and crawlspaces often need a larger unit, and a dehumidifier that runs nonstop is usually undersized.

How this size is worked out

The starting point is the sizing table published by the Association of Home Appliance Manufacturers (AHAM), which gives pints of water removed per day for spaces from 500 to 2,500 square feet in four dampness conditions. Your area is rounded up to the next 500 square feet. Above 2,500 square feet the table's own step is continued: 4 to 7 more pints for each extra 500 square feet, depending on dampness.

Since June 2019 the U.S. Department of Energy has tested portable dehumidifiers at 65°F instead of the warmer air in the older AHAM method, so the same unit now carries a lower pint rating. Retailers publish conversions of roughly 50 old pints to 35 new and 70 old to 50 new; the calculator multiplies by 0.7 to match. Shop by the new number.

The sizing table (older AHAM rating, pints per day)

AHAM dehumidifier sizing, pints per day by area and dampness
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

When to size up

Cool basements and crawlspaces: dehumidifiers remove less water in cool air.
Open floor plans or a basement open to the rest of the house.
Drying after a leak or flood. That is a different job; restoration shops use commercial units sized to the loss.
A unit that runs nonstop and never reaches its set humidity is undersized.

Questions

What humidity should I aim for?

The EPA recommends keeping indoor relative humidity below 60 percent, ideally between 30 and 50 percent, to limit mold growth.

Why does my old 70-pint dehumidifier look like a 50-pint model now?

The U.S. Department of Energy changed the test to 65°F air in 2019, which lowers the pint rating for the same machine. Compare units on the same rating.

Will a household dehumidifier dry out water damage?

Not on its own. After a leak, wet drywall, framing, and flooring need extraction and drying equipment sized to the loss. Call a water damage shop.