A musty smell in the basement, condensation on the windows, or a bathroom that never quite dries out — these are all signs your home has too much moisture in the air. Learning how to choose a dehumidifier is the fastest way to fix that, because the right unit quietly pulls gallons of water out of the air every day and keeps humidity in the healthy range. The wrong one, meanwhile, runs constantly, fills its bucket in hours, and barely moves the needle.
Quick answer: For most homes, a 30- to 50-pint compressor dehumidifier with a built-in humidistat and a continuous-drain option is the right starting point. Match the pint capacity to your room size and how damp the space really is, pick a desiccant model instead if the room stays below about 60°F, and make sure you have a drainage plan so the unit never stops on a full bucket.
1. Start With Your Room Size and How Damp It Really Is
Capacity is the first decision, and it depends on two things: how big the space is and how wet it is. A 1,000-square-foot basement that only smells musty on humid days needs far less capacity than the same basement with damp patches at the base of the walls.
- Bedroom or office (100–500 sq ft): a 20- to 22-pint unit is usually enough.
- Living room or small apartment (500–1,500 sq ft): look at 30- to 35-pint models.
- Basement or large main floor (1,500–3,000 sq ft): a 50-pint unit is the standard choice.
- Very damp or wet spaces: go up one size class, or plan on two units for a large split basement.
One trap to watch for is the pint rating itself. In 2019, the US Department of Energy changed the test conditions from 80°F to 65°F, and because less moisture condenses out of cooler air, every number on the box dropped by roughly 30%. An old “70-pint” unit and a new “50-pint” unit may be nearly the same machine, so compare models using current ratings only — multiply an old rating by about 0.7 to convert it.
If you are between two sizes, choose the larger one, as long as it has a humidistat. A slightly oversized unit reaches its target humidity, switches off, and idles, so it costs little more to run than a smaller unit straining all day.
2. Compressor or Desiccant: Match the Machine to the Temperature
Compressor dehumidifiers
Most portable dehumidifiers use a compressor and a cold coil to condense moisture out of the air. They offer the most capacity per dollar and the lowest running cost per pint, and they work best in rooms above about 60°F. The trade-off is that they lose efficiency as the temperature drops, and many need an auto-defrost cycle to keep ice from forming on the coils.
Desiccant dehumidifiers
Desiccant models use a moisture-absorbing wheel instead of a compressor, so they keep working in cold spaces where compressor units struggle — unheated garages, crawl spaces, and basements that sit below 65°F. They are usually quieter and lighter, but they use more electricity per pint and add a little warmth to the room.
- Room stays above 60°F: a compressor model is the efficient default.
- Room regularly drops below 60°F: a desiccant model is the safer pick.
- Whole-house or very large spaces: consider a ducted or whole-house unit installed with your HVAC system.
3. How the Water Gets Out: Bucket, Hose, or Pump
A dehumidifier is only as useful as its drainage plan. Every pint it removes has to go somewhere, and the method you choose decides whether the unit runs around the clock or stops every few hours.
- Bucket: every portable unit has one, and every bucket fills up. A 50-pint unit in a wet basement can fill a standard bucket in a single day. Fine for a bedroom, frustrating for a basement.
- Continuous drain hose: most mid-size and large units have a gravity drain outlet. Run a garden hose to a floor drain or sink and the unit never stops on a full bucket. This is the single most useful feature for a basement.
- Built-in pump: a pump lets you drain upward or across the room to a sink or window, which matters when no floor drain is nearby. It adds cost, but it is the only hands-off option for many basements.
Before you buy, check where the water will go. If there is no drain within hose reach, either budget for a pump model or accept that you will be emptying a bucket every day.
4. Features That Actually Matter
Once capacity, type, and drainage are settled, a few features separate a good machine from a merely adequate one.
- Humidistat: a built-in humidistat lets you set a target — 45 to 50% relative humidity is the usual goal — and the unit cycles on and off to hold it. Without one, the machine just runs until you switch it off.
- Auto-defrost: essential for compressor models in cool rooms. It melts frost off the coils so the unit keeps working instead of icing up.
- ENERGY STAR certification: certified models use roughly 10–20% less electricity than standard models, which adds up for an appliance that may run for months at a time.
- Noise level: check the decibel rating if the unit will sit in a bedroom or living room. Basement units can be louder without anyone noticing.
- Washable filter: a reusable filter you can rinse beats buying replacements, and it keeps airflow — and performance — from dropping as dust builds up.
- Auto-restart: after a power outage, the unit resumes at your settings instead of sitting idle until you notice.
A separate hygrometer is a cheap, useful companion. Built-in humidity readouts are often off by several percentage points, so a standalone meter tells you whether the unit is actually doing its job.
5. What a Dehumidifier Can’t Fix
A dehumidifier treats water vapor in the air. It does not stop liquid water coming through a wall, floor, or roof. If you have seepage after rain, a plumbing leak, or a failed gutter, fix that source first — no portable unit can economically overcome active water entry.
It also cannot dry a flooded room on its own. For standing water, remove the water first, then let the dehumidifier handle the damp air and surfaces that remain. And while it reduces the conditions mold and dust mites need — aim to keep indoor humidity between 30% and 50% — it is not a substitute for cleaning up existing mold.
For airborne particles as well as humidity, see our guide to choosing the right air purifier.
Our Picks for Cleaner Indoor Air
We found no published dehumidifier products on the site to link here, so the picks below are the two published air purifiers that tackle indoor air quality alongside humidity control.
- LEVOIT Core 300S Smart Air Purifier — WiFi-Enabled H13 HEPA Purifier — a compact WiFi-enabled HEPA purifier that helps keep the air in a bedroom or office cleaner while a dehumidifier handles the humidity.
- Coway Airmega Mighty2 Air Purifier (AP-1512N, White) — a larger-room purifier that tackles indoor air quality alongside humidity control in living rooms and open-plan spaces.
FAQ
What humidity level should I set my dehumidifier to?
Aim for 45 to 50% relative humidity. Below 30% the air feels dry and can irritate skin and sinuses; above 60% mold, dust mites, and condensation become much more likely. A setting around 45% is a good year-round target for most homes.
How big a dehumidifier do I need for a basement?
For a basement up to about 1,500 square feet that is moderately damp, a 35-pint unit is a reasonable starting point. For a larger or very damp basement, step up to a 50-pint model with a continuous drain hose or a built-in pump, so it never stops on a full bucket.
Do dehumidifiers use a lot of electricity?
They use a noticeable amount — a typical 50-pint compressor unit draws roughly as much power as a small refrigerator running for long stretches. ENERGY STAR-certified models use about 10–20% less energy, and a humidistat saves the most, because the unit switches off once it reaches your target instead of running all day.
Can I leave a dehumidifier running all the time?
Yes, if it has a humidistat and a drain hose or pump. The humidistat stops the compressor once the target humidity is reached, and continuous drainage means the bucket never fills. With a bucket-only unit, expect to empty it daily in a damp space — or the unit will shut itself off when the bucket is full.
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