What Size Dehumidifier Do I Need for a Basement?
Pick the pint range from how damp the basement is, then check the 65°F frost note.
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Pints for a basement under 2,000 sq ft
| Condition without dehumidification | What you notice | Pints per 24 hours | Source |
|---|---|---|---|
| Slightly to moderately damp | Musty odor, 50-75% RH | 20-30 | ENERGY STAR |
| Very damp | Damp smell, damp spots, 75-90% RH | 25-40 | ENERGY STAR |
| Wet | Walls or floor sweat, seepage, laundry drying, 90-100% RH | 30-50 | ENERGY STAR |
Capacity is measured in pints per 24 hours. The column above is the small-to-medium room, under 2,000 sq ft. A basement over that floor area uses the large-room column on the 2,000 sq ft dehumidifier page.
How to size it
Name the condition from what the basement actually does, then read one row. A musty odor without wet surfaces is the 20-30 pint row. Damp spots on walls or floors, with RH in the 75-90% band, is the 25-40 pint row. Sweating walls, seepage, or laundry drying in the room, at 90-100% RH, is the 30-50 pint row. If you are between two descriptions, ENERGY STAR's rule for dehumidifiers is the opposite of the air-conditioner warning: "It's better to oversize than undersize!"
The 30 pint mark sits in every small-to-medium range: it is the top of 20-30, inside 25-40, and the bottom of 30-50. That is why a 30 pint ENERGY STAR model is the search under the answer. A wet basement that is already at the sweaty end of the chart should not stop at the bottom of 30-50 if a larger pint capacity in that range is what "oversize" means for that row.
Basements are the usual place the temperature warning matters. Below 65°F, frost can form on the coils, and a frosted coil is not delivering the pint rating you sized. Consider a model specified for lower temperatures, or one with an anti-frost sensor. The chart does not print a separate pint table for cold rooms. It changes the product feature you shop for.
After it is running, the target is not "as dry as possible." Optimum indoor RH is generally 30-50%. In a cold climate during the heating season, ENERGY STAR tightens that to 30-40% to prevent window condensation. A hygrometer is how you tell 50-75% from 75-90% from 90-100% instead of guessing which row you were in. Keep doors and windows closed while the unit runs, or the pint rating is being spent on outdoor air.
ENERGY STAR certified dehumidifiers use 20% less energy than conventional units. The efficiency metric is integrated energy factor, in liters per kilowatt-hour. The source does not publish a single IEF number to aim for, so this page does not invent one.
If RH stays above 55% in a humid climate and the house has central air, ENERGY STAR points to a whole-home dehumidifier rather than only a portable in the basement. The cooling side of that central system is a load calculation, not a pint rating.
Related questions
- What size dehumidifier for 2,000 sq ft
- What size air conditioner for 700 sq ft
- What size air conditioner for 2,000 sq ft
All of these questions are listed on the topic map.
Sources
- ENERGY STAR, Dehumidifiers — https://www.energystar.gov/products/dehumidifiers — accessed Oct 2, 2026.
Frequently asked questions
What size dehumidifier does a basement need?
For a small-to-medium space under 2,000 sq ft, ENERGY STAR lists 20-30 pints per 24 hours when it is slightly to moderately damp, 25-40 pints when it is very damp, and 30-50 pints when it is wet. Match the description. Do not average the three rows.
What relative humidity are those rows tied to?
Slightly to moderately damp is a musty odor at 50-75% RH. Very damp is 75-90% RH, with damp spots on walls or floors. Wet is 90-100% RH, when walls or floors sweat, moisture seeps in, or laundry is drying in the room. The indoor target is generally 30-50% RH, or 30-40% in a cold climate during the heating season.
Why does a cold basement need a different model?
Below 65°F, frost can form on the coils. ENERGY STAR says to consider a model specified for lower temperatures or one with an anti-frost sensor. The pint ranges assume the unit can keep running.
Is bigger always wrong, the way it is for an air conditioner?
Not on this chart. ENERGY STAR says it is better to oversize than undersize a dehumidifier. Certified units use 20% less energy than conventional ones. If the basement is not under 2,000 sq ft, use the large-room column instead. A central cooling load is a separate step on the HVAC load calculator.