Basement Dehumidifier Size Calculator
- Uses the current DOE pint ratings
- Accounts for laundry, showers and cool basements
- Estimates monthly running cost
What size dehumidifier do I need for my basement?
For most basements, the answer is a 35-pint or 50-pint dehumidifier. The right size depends on two things: how much space you need to dry and how damp it is. A small, mildly musty basement can get by with a 22-pint unit, while a large or wet basement needs a 50-pint model or a whole-basement system. When in doubt, size up. An undersized dehumidifier runs nonstop and never gets the humidity down.
| Basement size | Moderately damp | Very damp | Wet | Extremely wet |
|---|---|---|---|---|
| 500 sq ft | 22-pint | 22-pint | 22-pint | 35-pint |
| 1,000 sq ft | 22-pint | 35-pint | 35-pint | 50-pint |
| 1,500 sq ft | 35-pint | 35-pint | 50-pint | 50-pint |
| 2,000 sq ft | 35-pint | 50-pint | 50-pint | 50-pint |
| 2,500 sq ft | 50-pint | 50-pint | 50-pint | Whole-basement |
| 3,000+ sq ft | 50-pint | 50-pint | Whole-basement | Whole-basement |
Why dehumidifier sizes changed in 2019
In 2019 the Department of Energy changed how dehumidifiers are tested, from warm 80°F conditions to a cooler 65°F that better matches real basements. Cooler air holds less moisture, so every unit’s rating dropped even though the machines didn’t change. A unit sold as a 70-pint before 2019 is now labeled about 50 pints, and an old 50-pint is now roughly 35 pints. Older sizing charts and reviews still use the old numbers, so make sure you’re comparing current ratings. The calculator above uses the 2019 standard.
Features that matter in a basement
- Drain options. Emptying a bucket once or twice a day gets old fast. If there’s a floor drain or sump pit nearby, run a hose to it. If not, a model with a built-in pump can push water up to a sink or out a window.
- Low-temperature operation. Standard units can frost over below about 65°F. Unfinished basements often run cooler, so look for auto-defrost and a low operating range.
- A built-in humidistat. Set it and the unit cycles on and off to hold your target, instead of running constantly.
- ENERGY STAR certification. Certified models remove the same water with noticeably less electricity, which adds up over a long humid season.
- Auto-restart. The unit turns itself back on at your settings after a power outage.
What humidity should a basement be?
The EPA recommends keeping indoor humidity between 30% and 50%, and ideally below 60% to discourage mold and dust mites. For most basements, setting the dehumidifier to 45–50% is the sweet spot. It’s dry enough to stop musty smells and mold, without running the unit harder than necessary. A cheap digital hygrometer helps you confirm the reading, since built-in sensors can be off by a few points.
Getting the most out of your dehumidifier
- Place it near the center of the space, or near the dampest area, with at least a foot of clearance around it.
- Keep basement windows and doors closed while it runs.
- Clean the air filter every few weeks during heavy use.
- Wrap cold-water pipes in foam insulation to stop them from sweating.
- Vent the dryer outside and make sure gutters and downspouts carry water away from the foundation.
More tips in our guide on how to dehumidify a basement.
Portable vs. whole-basement dehumidifiers
Portable units cost $150–$320 and handle most basements up to about 2,500 sq ft. Whole-basement dehumidifiers remove roughly 70–120 pints a day, drain continuously, and can be ducted to reach closed-off rooms. They cost $1,200–$2,500 installed, but they’re quieter, more efficient and last longer. They make sense for large, very damp or finished basements with several rooms, and for encapsulated crawl spaces.
When a dehumidifier isn’t enough
A dehumidifier removes moisture from the air, but it can’t stop water that’s coming through the walls or floor. If you see puddles, a wet line where the wall meets the floor, or water after heavy rain, the fix is drainage or waterproofing. Price your options with our basement waterproofing cost calculator. Planning to finish the space? Get the moisture under control first, then use our basement finishing cost calculator.
Related guides
- How to dehumidify a basement
- Basement waterproofing cost calculator
- Moisture control mistakes to avoid
- Crawl space cleaning cost calculator
Frequently asked questions
What size dehumidifier do I need for a 1,000 sq ft basement?
A 22-pint unit can handle 1,000 sq ft if the basement is only damp in humid weather. If it always feels damp or musty, get a 35-pint model. If the walls sweat or you get seepage, a 35-pint is the minimum and a 50-pint gives more headroom.
Is a bigger dehumidifier better?
Within reason, yes. A slightly oversized unit reaches your target humidity faster and cycles off, while an undersized one runs constantly and may never catch up. Most portable units use similar power, so sizing up one step rarely costs much more to run.
How much does it cost to run a dehumidifier in a basement?
Most ENERGY STAR basement units cost about $10–$40 a month to run during humid months at typical electricity rates, depending on size and how damp the space is. Older or non-certified models can cost a third more.
Should a basement dehumidifier run all the time?
It should run whenever humidity is above your target. With the humidistat set to 45–50%, it switches on and off by itself. Many basements need it from late spring through early fall, and some year-round.
What is the difference between a 50-pint and a 70-pint dehumidifier?
Often nothing. Since the 2019 DOE testing change, units formerly sold as 70-pint are rated at about 50 pints. Check whether a listing uses the 2019 standard before comparing capacities.
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