A portable dehumidifier dries the air in one room or one floor of a home. Before you buy one, match its pint rating to the space, note the temperatures it can run in, and decide how its water will drain. At The Indoor Report, we recommend a specification instead of a model number.
The Environmental Protection Agency (EPA) advises keeping indoor relative humidity between 30 and 50 percent, and below 60 percent to limit mold growth.
A Portable Dehumidifier Treats One Room or One Floor
A portable dehumidifier treats the air in one room or one floor, so name the damp space before you shop. The unit rolls on wheels, has a carry handle and plugs into a wall outlet. You can move it from a damp bedroom to a laundry room, and it works on the air wherever it stands.
Before buying, match the rated pint capacity to the size and dampness of the space. Pick a unit that works at the room's temperature, and plan whether water leaves through a bucket, a gravity drain hose or a built-in pump. Our dehumidifier size guide covers the sizing arithmetic.
A portable unit treats only the air in the room it sits in. It does not dry a separate room behind a closed door, and it does not stop liquid water coming into the building. When every room needs drying, a ducted whole-house dehumidifier is the alternative to compare.
Compressor and Desiccant Units Behave Differently in Cold Rooms
Compressor units perform worse in cold rooms, while desiccant units keep working at lower temperatures. A compressor dehumidifier, also called a refrigerant unit, chills a coil so water condenses out of the air passing over it. In a cool basement or garage that coil can ice up, which is why compressor units struggle there.
A desiccant dehumidifier uses a moisture-absorbing material. It keeps working in lower temperatures. Our desiccant dehumidifier page covers that design in more depth.
Choose by the room's temperature during the damp months. A garage or an unheated basement favors a desiccant unit.
Our types of dehumidifiers guide compares the two designs side by side. Below-grade rooms get their own treatment on the basement dehumidifier page.
Pint Ratings Measure Daily Water Removal Under a Set Test
A pint rating states how many pints of water a dehumidifier removes from the air per day under a standard test, according to ENERGY STAR. That number describes the unit under test conditions. Your room on a given day may be warmer, colder, damper or drier than the test.
The 2019 change affects comparisons between older and newer ratings. ENERGY STAR notes that the U.S. Department of Energy switched that year to a cooler 65 degrees Fahrenheit test, so ratings published after the change are lower than older ratings for the same hardware. Compare a post-2019 pint number only with another post-2019 pint number.
Energy efficiency is a separate figure from capacity. ENERGY STAR lists dehumidifiers that meet its efficiency requirements and measures certified models in liters of water removed per kilowatt-hour. More liters per kilowatt-hour means more water out for the same electricity; see our running cost page.
| Figure | What It Measures | What It Leaves Out |
|---|---|---|
| Pints per day | Water removed from the air per day under the standard test, per ENERGY STAR | How the unit performs in your specific room |
| Pint rating published after 2019 | Capacity at the cooler 65 degrees Fahrenheit Department of Energy test, per ENERGY STAR | A fair match against a pre-2019 rating for the same hardware |
| Pint rating published before 2019 | Capacity under the older test conditions | A fair match against a post-2019 rating |
| ENERGY STAR certification | The model meets ENERGY STAR energy-efficiency requirements | Whether the unit suits a cold room |
| Liters per kilowatt-hour | Water removed for each kilowatt-hour of electricity on certified models | Total pint capacity per day |
Bucket, Gravity Drain or Pump Sets How Water Leaves the Unit
Most portable units collect water in a bucket that you empty by hand, and many also accept a hose for continuous gravity drain or include a built-in pump. The right choice depends on who is around to empty the unit and where the nearest drain sits.
Pick gravity drain or a pump for a room you rarely visit, such as a storage basement. A bucket suits a bedroom or office you use every day. Not every portable unit offers a hose connection or a pump, so look for those features in the specification when nobody will empty a bucket.
- Bucket: works when someone is home to empty it, and it needs no drain nearby.
- Gravity drain: many units also accept a hose for continuous gravity drain.
- Built-in pump: lifts water through the hose, so it can reach a sink or drain that sits higher than the unit.
Water left standing in the collection bucket can itself become a place for microbes to grow. Empty the bucket and clean it on the schedule the unit's manual gives.
Placement and Humidity Targets That Make a Unit Useful
Place a portable dehumidifier inside the damp room, because it treats only the air in the room where it sits. It does not dry a separate room behind a closed door.
For the distance from walls, follow the spacing in the unit's manual.
Set the humidity target from EPA guidance: 30 to 50 percent relative humidity, and under 60 percent to limit mold growth. A hygrometer in the room shows where the air sits, and our ideal humidity in house page covers that range in more detail.
EPA advises 30 to 50 percent relative humidity.
When a Portable Dehumidifier Is the Wrong Tool
A portable dehumidifier is the wrong tool when the dampness covers the whole house, when liquid water is coming in, or when the damp space is one the unit cannot sit inside.
Start with leaks. EPA says mold needs moisture and that the way to control mold is to control moisture, with leaks fixed first. A portable unit dries air and does not stop liquid water entering the building, so standing water calls for finding and repairing the source before a dehumidifier runs.
If a hygrometer shows several rooms above the 60 percent ceiling EPA gives for mold, one portable unit can only work on one room at a time. Compare a ducted whole-house dehumidifier for that case.
A crawl space is a separate space below the floor. A unit in the room above treats only that room's air, so a portable dehumidifier placed upstairs does not dry the crawl space.
Two conditions change our answer. If the room is cold, a desiccant unit is the better fit. If the dampness follows a leak, fix the leak first and only then decide whether the room still needs a unit.
Our small dehumidifier page covers compact units.
A Short Buying Checklist for Choosing a Portable Dehumidifier
Buy a portable dehumidifier when one room or one floor reads damp and no leak is feeding it. Work through these steps in order before you choose a unit.
- Take a hygrometer reading and compare it with the 30 to 50 percent relative humidity range EPA advises.
- Find and fix any leak or standing water first, since EPA says controlling moisture at the source controls mold.
- Note how cold the room gets in the damp months, and lean toward a desiccant unit for a cool basement or garage.
- Size the pint rating with our dehumidifier size guide, comparing post-2019 ratings only with other post-2019 ratings.
- Choose the water route: a bucket if someone will empty it, gravity drain through a hose if the unit offers one, or a pump if water must go up.
- Prefer a model that meets ENERGY STAR efficiency requirements, and compare liters per kilowatt-hour between certified models.
- Plan the spot inside the damp room, since the unit treats only the air in the room it sits in.
- Shortlist units that pass these steps on our best dehumidifier page, then set your portable dehumidifier to hold the room between 30 and 50 percent, the range EPA advises.
Common questions
How many pints do I need in a portable dehumidifier?
Match the rated pint capacity to the size and dampness of the room, and use our dehumidifier size guide for the arithmetic. Compare newer pint numbers only with other newer pint numbers.
Can a portable dehumidifier dry a whole house?
No, a portable dehumidifier treats the air in the room it sits in. It does not dry a separate room behind a closed door. When several rooms are damp, a ducted whole-house dehumidifier is the option to compare.
Do portable dehumidifiers work in a cold basement?
A desiccant unit keeps working in lower temperatures, while a compressor unit performs worse in a cold basement. The compressor design chills a coil to condense water, and in a cool space that coil can ice up. Choose a desiccant unit when the basement stays cold during the damp months.
Where should I put a portable dehumidifier?
Put it inside the damp room. A portable unit treats only the air in the room it sits in and does not dry a separate room behind a closed door. Follow the manual for spacing from walls.
Does a portable dehumidifier need to be drained?
Yes, the collected water has to go somewhere. Most portable units hold it in a bucket you empty, and many also take a hose for gravity drain or have a built-in pump that lifts water. Empty and clean the bucket as the manual directs, because standing water can grow microbes.
How long should a portable dehumidifier run?
Run it until a hygrometer shows the room between 30 and 50 percent relative humidity, the range EPA advises, and use it as needed to hold that range. Our running cost page explains what drives the electricity bill.
Can I compare an old pint rating with a new one?
No, ENERGY STAR says older and newer pint numbers should not be compared directly. The U.S. Department of Energy moved to a cooler 65 degrees Fahrenheit test in 2019, which lowered published ratings for the same hardware.