What size dehumidifier do I need for a 1,000 sq ft basement?

Under 2,000 square feet, so the smaller band applies: 20 to 30 pints per day if it is slightly to moderately damp, 25 to 40 if it is very damp, 30 to 50 if it is wet. Round toward the top of the band.

What size dehumidifier do I need for a 2,000 sq ft basement?

2,000 square feet exactly sits in the larger band, where the published cells are 30+, 40+ and 50+ depending on dampness. Because those cells have no upper bound, treat the number as a floor rather than a ceiling.

What size dehumidifier do I need for a 500 sq ft basement?

The same smaller band applies, because the published table splits at 2,000 square feet, not at 500. So the answer is still 20 to 30, 25 to 40 or 30 to 50 by dampness. A small basement is not automatically a small machine.

How many pints per day do I actually need?

Read it off the published table by dampness, then round up. The calculator on this site returns the suggested size and shows which cell it came from.

Is a bigger dehumidifier bad?

No. Unlike an air conditioner, a larger dehumidifier does not short-cycle into a comfort problem. It reaches the target humidity faster, runs fewer hours, and keeps capacity in reserve. That is why the published advice rounds toward the larger size.

Is a basement dehumidifier worth it?

That depends on what the water is doing. If the basement is damp because humid air settles there, a correctly sized unit fixes it and the running cost is the trade. If water is arriving through a wall or a floor, the machine runs continuously and loses, and the money is better spent on drainage first. Sizing is the second question.

My basement sits at 70% humidity. What size do I need?

70 percent relative humidity falls in the table's slightly to moderately damp tier, 50 to 75 percent, so the cell is 20 to 30 pints per day under 2,000 square feet. Note that the tier describes the space without a dehumidifier: if the reading only reaches 70 percent because a unit is already running, the room is worse than the tier suggests.

My basement is cold. Does that change the answer?

It can change whether any answer works. Below roughly 65 degrees Fahrenheit the coil can frost and the unit may cycle without removing water. Look for a unit specified for lower temperatures before you worry about pints.

What size dehumidifier do I need for a basement?

A basement is not just a room with a lower floor. The published sizing table gets you most of the way; two things about basements specifically decide whether the number it gives you is right.

Research review Goods Review Lab Last updated 11 October 2026 Capacity bands from the published ENERGY STAR sizing table, on the current DOE rating basis

In short

The number you are looking for: Under 2,000 ft², a slightly to moderately damp basement takes 20–30 pints per day, a very damp one 25–40, and a wet one 30–50. Over 2,000 ft² the published cells read 30+, 40+ and 50+.
Where those numbers come from: The published ENERGY STAR dehumidifier sizing table, which is the AHAM-derived chart, split by floor area and by how damp the space is without a dehumidifier.
The basement-specific catch: The table is by floor area. A basement is also the coldest room in most houses, and capacity ratings are measured at a fixed temperature. Below that temperature the machine you bought is not the machine the chart promised.
Which way to round: Up. The published advice is that it is better to oversize than undersize — a larger unit reaches the target faster and runs fewer hours.

The published table, applied to a basement

This is the whole chart. It has two axes: how big the space is, and how damp it is before you put anything in it. The three dampness descriptions are the table's own wording, not our paraphrase.

Published capacity bands, in pints per day, on the current DOE rating basis
Condition of the basement, without a dehumidifier	Under 2,000 ft²	2,000 ft² and over
Slightly to moderately damp — feels damp, musty odour that may come and go (50–75% RH)	20–30	30+
Very damp — consistently smells damp, damp spots on walls or floor (75–90% RH)	25–40	40+
Wet — walls or floor sweat, or seepage is present (90–100% RH)	30–50	50+

If you want the number for your own basement rather than a band, the dehumidifier calculator runs the same table and names the cell it used. A small basement is its own question, and the 500 sq ft page takes that size on its own terms.

The thing about basements the chart does not say

The chart assumes a room. A basement is a room with three properties that make it a different problem, and only one of them is captured by floor area.

Three ways a basement differs from the room the chart assumes

It runs cold: Capacity ratings are measured at a fixed test temperature. A cold basement is the reason that temperature was changed in the first place — see below. And below a certain point, the coil frosts.
Its dampness is often a water problem, not an air problem: A dehumidifier removes water from air. If water is arriving through a wall or a floor, the machine runs continuously and loses the argument.
Its floor area is not the whole story: The table is by floor area. A basement with an unusually low or high ceiling holds a different volume of air for the same footprint.

Why the number on the label changed, and why it matters here

This is the part most sizing pages leave out, and it is the reason two charts can disagree while both are honest. The US Department of Energy's test procedure for portable dehumidifiers now runs them at 65 °F instead of 80 °F. In ENERGY STAR's words, the change was made “to more accurately reflect expected performance in a basement setting.”

Read that again, because it is aimed directly at the question you asked: the standard was rewritten because of basements. The old 80 °F test was optimistic for exactly the room you are sizing. The hardware did not change; the number on the label did, and it went down. A unit sold years ago as a 60-pint machine is a much smaller machine on today's labels.

So when you compare a listing against an older chart — or against a page that still quotes the old AHAM 80 °F figure — check which basis each side is on first. Otherwise you are comparing two different measurements and will conclude one of them is wrong. Every number on this page is on the current basis.

The basement that is too cold for the machine

ENERGY STAR states that if the space being dehumidified typically falls below 65 °F, frost can form on the condensing coils, which can make the compressor cycle on and off repeatedly without removing moisture from the air. In that case the guidance is to switch the unit off and let it defrost, and to consider a product specified for lower temperatures in the first place.

This is the failure mode a sizing chart cannot warn you about. You can buy the correct capacity for the square footage, put it in an unheated basement in a cold month, and watch it do nothing — not because the size was wrong, but because the room was outside the range the machine was built for.

What the table does not cover

A whole house, or a sealed crawlspace. Those call for a ducted whole-home dehumidifier sized from a moisture-load calculation, not a portable unit sized from a room chart.
A basement far outside the area bands. Above the table's range the published cells are open-ended (“50+”), so the table stops being a sizing instrument and becomes a floor.
Standing water. That is past the table's last tier, and it is a drainage question before it is a capacity question.

Questions this page answers

What size dehumidifier do I need for a 1,000 sq ft basement?: Under 2,000 square feet, so the smaller band applies: 20 to 30 pints per day if it is slightly to moderately damp, 25 to 40 if it is very damp, 30 to 50 if it is wet. Round toward the top of the band.
What size dehumidifier do I need for a 2,000 sq ft basement?: 2,000 square feet exactly sits in the larger band, where the published cells are 30+, 40+ and 50+ depending on dampness. Because those cells have no upper bound, treat the number as a floor rather than a ceiling.
What size dehumidifier do I need for a 500 sq ft basement?: The same smaller band applies, because the published table splits at 2,000 square feet, not at 500. So the answer is still 20 to 30, 25 to 40 or 30 to 50 by dampness. A small basement is not automatically a small machine.
How many pints per day do I actually need?: Read it off the published table by dampness, then round up. The calculator on this site returns the suggested size and shows which cell it came from.
Is a bigger dehumidifier bad?: No. Unlike an air conditioner, a larger dehumidifier does not short-cycle into a comfort problem. It reaches the target humidity faster, runs fewer hours, and keeps capacity in reserve. That is why the published advice rounds toward the larger size.
Is a basement dehumidifier worth it?: That depends on what the water is doing. If the basement is damp because humid air settles there, a correctly sized unit fixes it and the running cost is the trade. If water is arriving through a wall or a floor, the machine runs continuously and loses, and the money is better spent on drainage first. Sizing is the second question.
My basement sits at 70% humidity. What size do I need?: 70 percent relative humidity falls in the table's slightly to moderately damp tier, 50 to 75 percent, so the cell is 20 to 30 pints per day under 2,000 square feet. Note that the tier describes the space without a dehumidifier: if the reading only reaches 70 percent because a unit is already running, the room is worse than the tier suggests.
My basement is cold. Does that change the answer?: It can change whether any answer works. Below roughly 65 degrees Fahrenheit the coil can frost and the unit may cycle without removing water. Look for a unit specified for lower temperatures before you worry about pints.

Where these numbers come from

The capacity bands, the three dampness descriptions and the note about spaces below 65 °F are from ENERGY STAR's dehumidifier sizing guidance and its page on dehumidifier testing and capacity. The 65 °F test temperature and the reason for it are stated on the same programme's testing page. The underlying test procedure is 10 CFR 430 Appendix X1. Nothing on this page is a test result, and no number here was estimated.