What Size Dehumidifier Do I Need? (Pint Chart by Room Size)
Quick answer
Choose by how damp the space is, then by its size. Under the current ENERGY STAR guidance, a moderately damp room under 2,000 sq ft needs 20–30 pints per day, a very damp one 25–40 pints, and a wet basement with sweating walls 30–50 pints. Spaces over 2,000 sq ft need 30, 40 or 50+ pints. When in doubt, buy the larger size: it removes moisture faster and runs less.
A dehumidifier that is too small runs all day and never reaches your target humidity. One that is the right size gets the space to 45–50% and then cycles off. Here is how to size it properly, including the rating change that confuses most shoppers.
How dehumidifier size is measured
Capacity is listed in pints of water removed per day (24 hours). In 2019 the U.S. Department of Energy changed the test conditions from a hot, humid 80°F room to a cooler 65°F, closer to a real basement. The same machine now gets a lower number. That is why a unit once sold as “70 pints” is now often labeled about 50 pints. ENERGY STAR notes that capacity options have changed for this reason (ENERGY STAR: Dehumidifiers).
| Old rating (before 2019) | Approximate new rating |
|---|---|
| 30 pints | 20 pints |
| 50 pints | 35 pints |
| 70 pints | 50 pints |
Dehumidifier size chart
ENERGY STAR sizes portable dehumidifiers by the condition of the space without dehumidification and by its area:
| Condition | Room under 2,000 sq ft | Room over 2,000 sq ft |
|---|---|---|
| Slightly to moderately damp: feels damp, musty odor at times (50–75% RH) | 20–30 pints | 30+ pints |
| Very damp: always feels and smells damp, damp spots on walls or floor (75–90% RH) | 25–40 pints | 40+ pints |
| Wet: walls or floor sweat, seepage, laundry drying (90–100% RH) | 30–50 pints | 50+ pints |
How to size yours in 4 steps
- Measure the area. Multiply length by width for each room the unit will serve. An open basement counts as one space.
- Measure the humidity. Leave a hygrometer in the space for a day. Readings above 60% mean you need a dehumidifier; see the ideal indoor humidity level.
- Judge the condition. Musty now and then is “moderately damp”. A constant damp smell and spots on walls is “very damp”. Water on walls or floor is “wet”.
- Pick from the chart, then round up. ENERGY STAR advises that it is better to oversize than undersize. Also size up for high ceilings, a laundry area, or a hot tub nearby.
Already own one? ENERGY STAR suggests judging by how much water you empty each day. If the bucket fills daily and the room still feels damp, you need more capacity.
Choosing by room
- Bedroom or small room (under 500 sq ft): a 20-pint unit, or a mini dehumidifier only for a closet or very small space.
- Basement: 35 to 50 pints for most basements, with a continuous drain hose or built-in pump so you don’t empty a bucket. Our guide on cleaning a basement helps with dust and debris once it is dry.
- Whole house: if several floors stay humid, a ducted whole-home dehumidifier installed by an HVAC contractor is usually more efficient than several portable units.
Features worth paying for
- ENERGY STAR certification: certified models use about 20% less energy than conventional units of the same size.
- Adjustable humidistat: set it to 45–50% so it cycles off once the job is done.
- Continuous drainage or a pump: essential for basements.
- Low-temperature operation: auto-defrost if the space drops below about 65°F.
- Washable filter: clean it every few weeks to keep airflow strong.
A dehumidifier controls moisture but doesn’t filter much from the air. If you also want cleaner air, see using an air purifier and dehumidifier together and does a dehumidifier purify the air.
Frequently asked questions
Can a dehumidifier be too big?
Not in a harmful way. A larger unit reaches the target humidity sooner and then shuts off. The only downsides are price, size and noise.
What size dehumidifier do I need for a 1,000 sq ft basement?
For a damp but not wet basement, 25 to 35 pints under the new ratings. If walls sweat or water seeps in, choose 40 to 50 pints and fix the water source.
Is a 50-pint dehumidifier the same as a 35-pint?
Often, yes. Many models once rated at 50 pints under the old test are rated about 35 pints under the 2019 test. Compare models using the same standard.
What humidity should a dehumidifier be set to?
45–50%. Lower settings use more electricity without much added benefit.