Buying Guide

How to Choose the Right Size Dehumidifier

How Dehumidifiers Work
A person removes the drain tank of a 95-pint dehumidifier.

Dehumidifiers regulate humidity by drawing moisture from the air. A fan pulls the moist air into the dehumidifier and through cooling coils, which use condensation to draw dampness from the air. The dehumidifier’s heat recovery system then passes warmer, dryer air back into the room. The water collects in a removable drip pain or reservoir or is circulated out of the unit with some models. 

  • Many dehumidifiers come equipped with a humidistat, which measures and can set the relative humidity (rh) in a room. A 50 percent rh is recommended for summer, while in winter, the ideal rh can be as low as 30 percent. 
  • A whole-house dehumidifier may be needed if high humidity is a problem throughout your home. Some are portable appliances while others are built into and can operate as part of your HVAC system.
  • Desiccant dehumidifiers are designed to remove moisture from the air by using chemicals instead of condensation. They tend to be quieter and create lower humidity levels than other dehumidifiers, but have a more limited capacity, a noticeable aroma and are less economical than other types. 
Check the Room's Moisture Level
A person points out water damage on drywall near a floor.

A room with damp surfaces or a constantly musty odor may need a dehumidifier, which will need to work harder in an extremely wet space than one that’s mildly damp. You can use a humidity meter to measure a room’s moisture or assess it based on these general criteria: 


  • A space is considered damp if it has a musty aroma in humid weather or occasionally feels damp or clammy. 
  • A space is very damp if it is always damp and musty. 
  • A space is wet if it occasionally has visible condensation or the ceiling or walls. 
  • A space is very wet if it always has visible condensation or standing water. 


Note: If you detect excess moisture in a room, take steps to eliminate or reduce its source, such as repair leaks or clean a dryer’s lint filter. 

Measure the Room's Size
A person measures the size of a room with a tape measure.

Once you’ve determined that a room has excessive humidity, measure the room’s dimensions to determine the size humidifier you need. Use a tape measure to determine the room’s length and width and multiply to determine the square footage. For instance, a 12- by 12-foot room will have square footage of 144 feet. 

Compare Room Size vs. Moisture Level for Dehumidifier Size
A 70-pint dehumidifier sits in the corner of a living room.

Dehumidifier capacity is rated by the amount of moisture removed in 24 hours, so a 30-pint humidifier is rated to remove 30 pints of moisture in one day. 


Use a 30-pint dehumidifier (or a unit between 24- and 39-pint capacity) in the following conditions:

  • Damp rooms of 500-1,500 square feet 
  • Very damp rooms of 500-1,000 square feet 
  • Wet and extremely wet rooms of 500 square feet 


Use a 50-pint dehumidifier (or a unit between 40- and 59-pint capacity) in the following conditions: 

  • Damp rooms of 2,000-2,500 square feet 
  • Very damp rooms of 1,500-2,000 square feet 
  • Wet rooms of 1,000-1,500 square feet 
  • Extremely wet rooms of 1,000 square feet 


Use a 70-pint dehumidifier (or one with 60-pint capacity or greater) in the following conditions: 

  • Very damp rooms of 2,500 square feet 
  • Wet rooms of 2,000-2,500 square feet 
  • Very wet rooms of 1,500-2,500 square feet 
Other Factors in Choosing Dehumidifier Size
A girl and a pet rabbit play in a room near a dehumidifier.

Other factors can influence the humidity of the room, so consider the following when sizing a dehumidifier: 

  • If your home is in a humid climate, add 10 pints to the recommended capacity. 
  • If multiple people live or spend time in the room, add 5 pints. 
  • If the room has multiple windows or doors, add 5 pints. 
  • If a washer/dryer is in or near the room, add 5 pints. 


Tip: In some circumstances, a dehumidifier that seems slightly larger than you need may hold advantages. You can run it on a lower setting, possibly reducing electricity usage and bringing down your energy bills. A dehumidifier that you can run on a lower setting also means a lower noise level. 

High humidity can lead to mildew and mold growth and even make your home more attractive to roaches, spiders and other insects that prefer moist environments. Choosing the right size dehumidifier for your basement, laundry room or other interior space can put humidity control at your fingertips.