Dehumidifier Size Calculator
Find the dehumidifier size your basement or room needs from its square feet and how damp it gets, in today's pint ratings and the older ones.
A dehumidifier is sized by the space and by how damp it gets. One more thing trips people up: since 2019, dehumidifiers are rated at cooler, basement-like conditions, so the same machine carries a smaller number than it used to. This gives today's size and what it was called before.
Square feet of the space
The basement, crawl space or room you want to dry; most basements are 800 to 1,500 sq ft.
How damp is it?
Judge it on a humid summer day with no dehumidifier running.
Dehumidifier to buy
A 35-pint
For 1,000 sq ft that has damp spots
Sizes follow ENERGY STAR's chart, rounded up to the 22, 35 and 50-pint sizes most stores sell. Over 2,000 sq ft, or for a whole finished basement, ask about a whole-home dehumidifier. 2026 figures.
💡About this calculator▼
Dehumidifiers are sold by how many pints of water they can pull out of the air in a day, and the right size depends on two things: how big the space is and how damp it gets. A musty basement and one with water seeping in need very different machines.
This picks the size. Enter the square feet and choose how damp the space is on a humid day, and you get the dehumidifier size to buy, rounded up to the sizes stores actually sell.
It also clears up the numbers. Since 2019, dehumidifiers are rated at cooler, basement-like conditions, so the same machine now carries a smaller number than it did before. A 35-pint today is roughly what a 60-pint was. The calculator gives both, so an older chart or the label on your old unit doesn't steer you wrong.
ENERGY STAR's sizing chart. For a space under 2,000 square feet, ENERGY STAR recommends 20 to 30 pints a day if it's slightly to moderately damp (musty now and then), 25 to 40 if it's very damp (damp spots on walls or floors), and 30 to 50 if it's wet (walls sweat or water seeps in). Over 2,000 square feet the minimums are 30, 40 and 50.
Scaled by size. The calculator places your space within that range: the low end at 500 square feet, the high end at 2,000.
Rounded up to a real size. Most portable dehumidifiers are rated about 22, 35 or 50 pints, so the answer rounds up to the next of those; ENERGY STAR's advice is that it's better to oversize than undersize.
The older rating. Under the old test, the same machines were rated about 35, 60 and 80 pints.
Worked example. A 1,000-square-foot basement with damp spots: the very-damp range is 25 to 40, and 1,000 square feet is a third of the way from 500 to 2,000, so about 30 pints a day; that rounds up to a 35-pint, which an older chart would call about a 60-pint.
📐How it's calculated▼
Pints needed = low end + (high end − low end) × (square feet − 500) ÷ 1,500, for spaces of 500 to 2,000 sq ft, using ENERGY STAR's range for your condition: musty 20–30, damp spots 25–40, wet 30–50. Under 500 sq ft, the low end; over 2,000, the minimum of 30, 40 or 50.
Size to buy = the next of 22, 35 or 50 pints. Older rating: 22 ≈ 35, 35 ≈ 60, 50 ≈ 80.
1,000 sq ft, damp spots: 30 → a 35-pint (formerly about 60). 500 sq ft, musty: 20 → a 22-pint. 1,000 sq ft, wet: 37 → a 50-pint.
📎Sources:ENERGY STAR — Dehumidifiers (sizing chart by space and dampness),ENERGY STAR — Dehumidifier Testing and Capacity (old and new pint ratings),U.S. EPA — A Brief Guide to Mold, Moisture and Your Home
🔍Finding your inputs▼
Square feet of the space: The basement, crawl space or room you want to dry. If it's an open basement, the whole floor; if a door closes it off, just that room.
How damp is it: Judge it on a humid summer day with no dehumidifier running. A musty smell that comes and goes is the first; damp patches on walls or the floor are the second; sweating walls, seepage, or laundry drying down there is the third.
⚠️Special situations▼
What size dehumidifier do I need for a 1,000 sq ft basement?
A 35-pint (rated under today's test) if it has damp spots or just smells musty at times, and a 50-pint if the walls sweat or water seeps in. On an older chart those are about a 60-pint and an 80-pint. If yours is only occasionally musty and closer to 800 square feet, a 22-pint will do.
My old dehumidifier was a 70-pint. What do I replace it with?
About a 40- to 50-pint under today's ratings. ENERGY STAR's conversion puts an old 70-pint at roughly 40 to 45 pints on the new test, so a 50-pint is the like-for-like choice from the sizes on the shelf. It isn't a smaller machine; it's the same job measured at cooler, more realistic conditions.
What size for a crawl space?
Size it the same way, by its square feet and how damp it is, then check two things on the model: that it can run with a hose to a drain, since nobody empties a bucket in a crawl space, and that it's rated to work at the cool temperatures a crawl space sits at. Portable units remove less water below 65°F.
Can a dehumidifier be too big?
Not in a way that hurts. A bigger unit reaches your target humidity and shuts off sooner, and ENERGY STAR's own advice is that it's better to oversize than undersize. Too small is the real problem: it runs constantly and never gets the space dry.
❓Common questions▼
How do I know what size dehumidifier I need?
By the space's square feet and how damp it gets. For under 2,000 square feet, ENERGY STAR recommends 20 to 30 pints a day for a space that's musty now and then, 25 to 40 for one with damp spots, and 30 to 50 for one where walls sweat or water seeps in. Round up to a size that's sold: 22, 35 or 50 pints.
Why did dehumidifier pint ratings change?
In June 2019 the Department of Energy changed the test from 80°F to 65°F, closer to a real basement. Cooler air holds less water, so the same machine now removes, and is rated for, fewer pints. A former 50-pint is about a 30 today, a former 60-pint about a 35, and a former 70-pint about 40 to 45.
What humidity should I set my dehumidifier to?
Below 60 percent, and ideally between 30 and 50 percent, which is the EPA's guidance for keeping mold from growing. A cheap humidity meter, around $10 to $50 at a hardware store, tells you whether you're there.
What size dehumidifier for 2,000 sq ft?
A 35-pint if it's only musty at times and a 50-pint if it has damp spots or water. At that size, especially for a whole finished basement, a whole-home dehumidifier installed by an HVAC pro is worth pricing too.
Is a 50-pint dehumidifier too big for a small room?
No. It will just cycle off sooner. ENERGY STAR recommends erring larger, and a 50-pint unit also handles the wettest summer days better. The trade-offs are size, weight and price, not performance.
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