What Size Dehumidifier Do You Need?

First, determine the square footage of the area you want to dehumidify. Then find out how damp it really is. A hygrometer, a device that measures a room’s relative humidity, is helpful for that second task. You can find one for less than $10.

If the area is large—say, 1,200 square feet or more—determining the right size dehumidifier is a no-brainer. Whether the air in the room just feels slightly damp or there’s noticeable condensation, you’ll need a powerful unit to dry the air. Large-capacity portable dehumidifiers can fill that need in all but the wettest situations. 

The maximum amount of water that such a unit will remove is usually 50 to 60 pints per day. Among the 25 large-capacity machines in Consumer Reports’ dehumidifier ratings, 21 are marketed with that claim. (Our water-removal scores, however, show that not all are up to the task.) 

When a dehumidifier is collecting so much, it’s useful to have the water flow directly into a drain rather than having to empty the tank. Typically, dehumidifiers include a hose coupling so that you can attach a standard garden hose and let the water run into, say, a floor drain in your laundry room or a walk-in shower drain. Models with a pump let you move the water higher than the dehumidifier to empty into, say, a laundry sink.

Most of the dehumidifiers in CR’s ratings don’t have a pump. But Misha Kollontai, the CR engineer who leads our dehumidifier testing, says similar models are often available with pumps for about $30 more.

In a very big space, you might also want to post a fan in another part of the room to improve airflow and distribute the drier air. Your dehumidifier’s fan might not be powerful enough for the job, Kollontai says, because these machines are designed to balance fan power and noise mitigation.

“A fan that’s too big is going to make a dehumidifier overly noisy,” he says.

Rooms from 600 to just under 1,200 square feet that have small puddles, condensation, or mold need the same attention as a larger space. That means using a large-capacity dehumidifier, Kollontai says. 

And if the area includes a living space, consider the noisiness of the unit. You can find Consumer Reports’ evaluation of that in our dehumidifier ratings.

If you have an area of, say, 600 to 800 square feet that’s slightly damp or has a musty smell, a medium-capacity dehumidifier may solve your problem.

Wetter rooms as small as 400 square feet can also benefit from midsized units, which are designed to remove 30 to 39 pints of moisture per day. 

As a group, medium-capacity dehumidifiers are less noisy than larger models, which is useful when you’re trying to dry out the air in a living area. You’ll typically pay less for this size dehumidifier, but some can cost as much as a large model. 

Areas of less than 600 square feet typically call for a small-capacity dehumidifier. In general, they remove less water and are less expensive than larger-capacity models.

In CR’s ratings, the four recommended small-capacity dehumidifiers all score Excellent ratings in water removal. They also all get Very Good or Excellent ratings for noise—a key feature for closer quarters—and include a built-in fan. Only one has a pump.

In a bathroom, Lewis says, installing a good exhaust fan is probably a better way to control humidity than using a small dehumidifier. “That’ll suck all the moisture out in a few minutes,” he says.

Use this guide to help you choose the right dehumidifier size for your space. These figures—and Consumer Reports’ test results—rely on Department of Energy dehumidifier labeling standards, updated in 2019 to more accurately reflect how well they work in basements, where many of these units are used.

If you can’t find mention of the 2019 standard on the packaging or product information guide, check the model page on the manufacturer’s website. The retailer’s page may also display the information in the product details. 

If there’s too much moisture in most rooms in your house, you may be better off with a whole-house dehumidifier. (Consumer Reports doesn’t rate these.)

Whole-house dehumidifiers are available as portable units or as add-ons to an existing central heating and air conditioning system. Manufacturers say they can handle an area up to 5,000 square feet. These units are expensive, but because they remove so much moisture from the air, you can cut back on air conditioning.

And even the best dehumidifier won’t solve your problem if too much moisture from the outside is continually seeping into your home. Unclogging gutters and making sure downspouts are directing rainwater at least 5 feet from the house can make a huge difference. If puddles and water droplets on floors, walls, and windows remain or worsen, contact a water remediation expert, HVAC contractor, or business that seals basements from moisture. 

You may in fact need more than one solution, Lewis says. First, you’ll need to remediate, and then install a dehumidifier to keep residual moisture at bay.

And for musty crawl spaces—areas prone to mold growth—you may need an industrial-sized dehumidifier that can remove 70 or more pints of water per day. You can buy them yourself or through a contractor. These units typically have no tanks, so you’ll need to attach a drain line, according to Lewis. For proper airflow, you also may need specialized ducts. Unless you’re handy, leave those tasks to a professional.

Once you’ve got a dehumidifier up and running, it’s a good idea to check humidity levels again, Kollontai says. On many dehumidifiers, you can see the room’s relative humidity in the unit’s built-in digital display. But also pull out that hygrometer you bought and take readings in different areas of the room.

“If at full power your dehumidifier is only pulling your humidity down to 60 or 70 percent, you need a bigger dehumidifier,” Kollontai says. 

Below, we share some top-rated dehumidifiers in different size categories, all based on CR testing.

This category is designed to remove at least 40 pints per day. These recommended dehumidifiers go beyond that; they’re designed to remove 50 pints per day, and our tests showed they came closest to meeting their claims.

This category is designed to remove 30 to 39 pints per day. Only two medium-capacity models from our tests are recommended and both score an Excellent rating for water removal.

These machines are designed to remove less than 30 pints per day.