What Size Dehumidifier Do I Need for a Basement?
Capacity is the number to size by, and ENERGY STAR publishes a table for it. Match your basement’s dampness and square footage to one row and the pints per day follow.
For a basement under 2,000 square feet, ENERGY STAR recommends 20 to 30 pints per day if the space is slightly to moderately damp, 25 to 40 if it is very damp, and 30 to 50 if it is wet. Over 2,000 square feet, those minimums rise to 30, 40 and 50 pints. ENERGY STAR’s advice when you land between sizes is to go bigger.
| Condition without a dehumidifier | Under 2,000 sq ft | Over 2,000 sq ft | Our pick |
|---|---|---|---|
| Slightly to moderately damp, 50 to 75% RH: smells musty some of the time | 20 to 30 pints/day | 30+ | Frigidaire 35-pint on Amazon, $229.00 |
| Very damp, 75 to 90% RH: always feels and smells damp, with damp spots on walls or floor | 25 to 40 pints/day | 40+ | Midea Cube 50-pint on Amazon, $241.59 |
| Wet, 90 to 100% RH: walls or floor sweat, water seeps in, or laundry dries in the space | 30 to 50 pints/day | 50+ | Midea Cube 50-pint on Amazon, $241.59 |
Step 1: Work out how damp the basement is
The three conditions in the table come from what you can see and smell. A musty odor that comes and goes puts a basement in the first row. Damp spots on the walls or floor, or a smell that never leaves, put it in the second. Sweating walls, water seeping in at the base of the foundation, or a clothes rack that never dries put it in the third.
A hygrometer settles it: a few days of readings tell you which relative humidity band the basement sits in. Take readings after rain as well as in dry weather, and size for the wettest week.
Step 2: Measure the floor area
Multiply the length of the basement by its width. Count only the space the dehumidifier has to serve. A finished room with its door kept shut is its own space; an open unfinished basement with the stairwell open to the floor above is one large space.
Step 3: Read the pint rating the right way
Since June 2019, portable dehumidifiers have been rated under a Department of Energy test run at 65°F instead of 80°F. The same machine now carries a smaller number. ENERGY STAR’s conversion puts an old 70-pint rating at about 40 to 45 pints on the current test, and an old 50-pint rating at about 30 pints.
Sizing advice written before 2019 and any unit bought before then use the 80°F rating. A basement that did fine with a 50-pint unit from 2015 needs about a 30-pint unit on today’s ratings, and the ENERGY STAR table above already uses current-test figures.
Step 4: Treat coverage area as a secondary number
Most listings print a square footage next to the pint rating: 4,500 square feet for the Midea Cube 50-pint, 3,000 for the Frigidaire 35-pint and the Hisense 35-pint. The pint rating comes from the DOE test. Coverage is the manufacturer’s own figure, and it can disagree with itself: the Hisense listing title says 3,500 square feet while Hisense’s spec sheet says 3,000. Size by pints and use coverage only to break a tie.
Step 5: Check the coldest temperature the basement reaches
The current test runs at 65°F. A basement colder than that removes less water per day than the rating, so a basement that sits in the 50s through the damp season is a reason to move up a size. Below the unit’s rated minimum it should not be running at all. The Midea Cube and the Frigidaire are rated down to 41°F, and the Hisense down to 38°F.
Which of our picks fits which basement
A moderately damp basement under 2,000 square feet needs 20 to 30 pints, so the Frigidaire 35-pint covers it with room to spare and is the lowest-priced of the three picks.
A very damp or wet basement, or any damp basement over 2,000 square feet, is where the Midea Cube 50-pint earns its place. Its 50 pints clear the top of the very damp range and reach the top of the wet range for a small to medium basement, and it is the only pick that ships with a drain hose for continuous drainage.
A basement that runs cold, into the low 40s or the high 30s, points to the Hisense 35-pint, rated to keep running at 38°F. At 35 pints it fits a moderately or very damp space under 2,000 square feet.
Each pick has a full review: Frigidaire 35-pint review, Midea Cube 50-pint review and Hisense 35-Pint Compact review. The basement roundup compares all three side by side.
If you are replacing a dehumidifier
ENERGY STAR suggests sizing a replacement by how much water you empty each day. If the old unit filled its bucket more than once a day in the wettest weeks, the new one needs more capacity. A pint is one eighth of a gallon, so a unit pulling 30 pints a day collects close to 4 gallons. Read the old unit’s rating against the 2019 conversion above before you compare numbers.
What humidity to aim for
ENERGY STAR gives 30 to 50 percent relative humidity as the generally accepted range for a building and notes that anything above it may promote mold growth. Set the humidistat near 50 percent to start. If the unit runs nonstop and never reaches the setting, it is undersized for the space or the water is coming in faster than any portable unit can remove it.
When a bigger dehumidifier is the wrong fix
Standing water after rain, or water entering through cracks, is a drainage problem first. Fix it with a sump pump or regrading around the foundation before sizing a dehumidifier, because no portable unit keeps up with active seepage.
Is it bad to buy a dehumidifier that is too big?
No. ENERGY STAR’s guidance is that it is better to oversize than undersize.
What size dehumidifier for a 1,000 square foot basement?
On ENERGY STAR’s table, 20 to 30 pints if the basement is slightly to moderately damp, 25 to 40 if very damp, and 30 to 50 if wet. A 35-pint unit covers the first two; a wet 1,000 square foot basement calls for a 50-pint unit.
What size dehumidifier for a 2,000 square foot basement?
Two thousand square feet is the line between the table’s two columns. Use the larger column if the basement is at or over that size: at least 30 pints if moderately damp, 40 if very damp, 50 if wet.
Is a 50-pint dehumidifier the same as an old 70-pint?
Close. ENERGY STAR’s conversion puts an old 70-pint unit at about 40 to 45 pints under the current test, so a current 50-pint unit removes a little more than an old 70-pint one did under the same conditions.
Does coverage area matter at all?
Use it as a tiebreaker. The pint rating comes from the DOE test; the square footage on the box is the manufacturer’s claim.
Which size should you buy?
Size a basement dehumidifier by pints per day using ENERGY STAR’s table. Read the row for your basement’s dampness and the column for its square footage, then round up. For most damp basements under 2,000 square feet that points to a 35-pint unit; for very damp, wet or larger basements it points to 50 pints, and the Midea Cube 50-pint is the pick in that range.
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