Dehumidifier size chart
Smallest common unit, by its 2019 DOE pint rating, that meets the AHAM sizing guide. AHAM's figures date from the older 80 °F test; applying them to the cooler 2019 rating leaves extra margin for basements. Add 5 pints for each extra moisture source.
| Area | Moderately damp | Very damp | Wet | Extremely wet |
|---|---|---|---|---|
| 500 sq ft | 20 pint | 20 pint | 20 pint | 20 pint |
| 1,000 sq ft | 20 pint | 20 pint | 20 pint | 30 pint |
| 1,500 sq ft | 20 pint | 22 pint | 30 pint | 30 pint |
| 2,000 sq ft | 22 pint | 30 pint | 35 pint | 50 pint |
| 2,500 sq ft | 30 pint | 35 pint | 50 pint | 50 pint |
Old vs new pint ratings
In 2019 the Department of Energy changed how dehumidifiers are tested, from 80 °F and 60% humidity to 65 °F and 60% humidity, which is closer to a real basement. Cooler air holds less water, so the same machine now earns a lower pint rating.
| Older rating (pre-2019) | Current 2019 DOE rating | Typical use |
|---|---|---|
| 30 pint | about 20–22 pint | Small room or closet |
| 50 pint | about 35 pint | Damp bedroom or small basement |
| 70 pint | about 50 pint | Most basements |
| 100+ pint (whole house) | about 70–130 pint | Ducted, whole-house units |
When you compare models, check which rating the box shows. A "50 pint (2019 DOE)" unit removes about as much water as an old "70 pint" one.
Getting the most from a dehumidifier
- Set it to 45–50% relative humidity. Below 30% feels dry; above 60% lets mold and dust mites grow.
- Use a continuous drain hose to a floor drain, or a model with a built-in pump, so you don't have to empty the bucket.
- Keep doors and windows to the space closed while it runs.
- Most standard dehumidifiers lose capacity and can ice up below about 65 °F. For cold basements and crawlspaces, choose a low-temperature or commercial-grade model.
- Fix the source if you can: gutters and downspouts that dump water near the foundation are the most common cause of a wet basement.
Frequently asked questions
What size dehumidifier do I need for a basement?
A very damp 1,000 sq ft basement needs at least a 20 pint unit (2019 DOE rating), and a wet one about 20 pints. Go one size larger if the basement is cool or you also want to dry laundry there.
Is a bigger dehumidifier better?
Within reason, yes. A larger unit reaches the target humidity faster and cycles less, which often uses less energy than a small unit running nonstop. Avoid going more than one size up for a small room.
What humidity should a basement be?
Between 45% and 50% relative humidity. That is low enough to stop mold and musty smells without drying out wood.
Does a dehumidifier need to run all the time?
No. With the humidistat set to 50%, it turns on and off by itself. In summer it may run most of the day in a damp basement.
What size dehumidifier for a crawlspace?
Encapsulated crawlspaces usually use a dedicated crawlspace unit of 70 to 100 pints (2019 DOE) designed to run in cooler, tighter spaces.
These results are estimates based on the AHAM sizing guide. Persistent water problems may need drainage or foundation repair rather than a larger dehumidifier.