HowMuchIt / Dehumidifier
What size dehumidifier do I need?
Dehumidifiers are sized in pints of water removed a day. Measure the damp space, judge how damp it is, and compare with the 2020 ratings: the numbers changed, and old ratings read higher.
Work out your dehumidifier
| Damp space | Capacity |
|---|---|
| About 400 sq ft | about 20 pints a day |
| About 1,200 sq ft or more | about 50 pints a day |
| Old 30 pints | new 20 pints |
| Old 50 pints | new 30 pints |
Since the 2019 rule, units are tested at 65 deg F instead of 80, so the same machine shows fewer pints.
How damp is damp?
Slightly damp means the space feels damp and smells musty now and then. Very damp means it always smells musty and damp spots show on the walls and floor. Wet means the walls or floor sweat, or water seeps in. The damper the space, the more capacity it needs for the same floor area, so a wet basement takes more than the chart's dry minimum. Measure the area first: length times width, in feet.
Why new units show fewer pints
From the 2019 rule, dehumidifiers are tested at 65 degrees Fahrenheit instead of 80. Cooler air holds less water, so the same machine now shows a smaller number: an old 30-pint rating is about a new 20, and an old 50 is about a new 30. Compare like with like. Indoors, a common target is 30 to 50 percent relative humidity.
Questions people ask
What size dehumidifier for a 600 sq ft basement?
Between the chart's two points: more than a 20-pint unit and up to a 50 if it is wet. The maker's chart for your model narrows it.
Is an old 70-pint the same as a new 50-pint?
Our two sources disagree on that conversion, so we leave it out; they do agree that an old 50 is about a new 30.
What humidity should I set?
A common target is 30 to 50 percent.
Good to know
- Measure the floor area first: room length times width, in feet.1,2
- Slightly damp: the space feels damp and smells musty now and then.3,4
- Very damp: the space smells damp or musty and damp spots appear on walls and floors.3,4
- Wet: the walls or floor sweat, or water seeps in.3,4
- The DOE test changed (rules from June 2019, new ratings from 2020): units are now tested at 65 deg F instead of 80 deg F, so the same machine shows a lower pint number.5,6
- Old (2019 and earlier) to new rating: about 30 pints became 20 pints, and 50 pints became 30 pints.5,6
- About 400 sq ft of damp space: a 20-pint unit on the 2020 rating.1,6
- About 1,200 sq ft or more: a large unit of about 50 pints a day on the 2020 rating.1,6
- A common indoor target is 30 to 50 percent relative humidity.3,7,8
How we checked this page
Checked on October 27, 2026. We kept a fact only when two independent publishers agree, and each one is numbered to its sources below. Where sources give different numbers, we keep only what they share. We never write a price. This page was written with an AI assistant and checked against the sources below.
Sources
- How Do I Know What Size Dehumidifier I Need?, Consumer Reports
- How to Choose a Dehumidifier: Sizing and Selection Guide, Thedryair (AlorAir dealer)
- Dehumidifiers, ENERGY STAR
- Dehumidifier Sizing Guide, Frigidaire (Electrolux)
- Dehumidifier Testing and Capacity, ENERGY STAR
- Dehumidifier Testing Standards and Product Pint Capacity, TCL
- A Brief Guide to Mold, Moisture and Your Home, US EPA
- What Is the Best Humidity Setting for a Dehumidifier?, Aire Serv (Neighborly)