A dehumidifier will not cool your room, but it may feel cooler
A dehumidifier removes moisture from the air, not heat. The machine pulls humid air across cold coils, water condenses and drains away, and the air passes over a warm compressor before returning to the room. That warm air often leaves the room at nearly the same temperature it entered — sometimes slightly warmer.
However, a room with lower humidity often feels cooler because sweat evaporates from your skin more easily. At 30% humidity, 72°F feels noticeably more comfortable than 72°F at 70% humidity. This is the "feels like" effect, not actual cooling. Your thermometer will not move, but your body's comfort will improve.
If you want actual temperature reduction, you need an air conditioner, which removes both heat and moisture. A dehumidifier is a comfort tool for damp spaces, not a replacement for cooling.
Key Takeaways
- Dehumidifiers remove moisture but add slight heat to the room, so the air temperature stays the same or rises slightly.
- Lower humidity makes the same temperature feel more comfortable because sweat evaporates faster from your skin.
- A dehumidifier works best in already-cool spaces where dampness is the main problem, not heat.
- If your room is hot, an air conditioner cools and dehumidifies at once; a dehumidifier alone will not lower the temperature.
- Running a dehumidifier in a sealed room will gradually warm the space as the compressor releases heat.
Why dehumidifiers produce heat instead of cold
A dehumidifier works by circulating room air over refrigerated coils. The moisture in the air condenses on these cold coils and drips into a tank or drain line. The now-dry air then passes over the warm compressor — the part that does the cooling work — before the fan pushes it back into the room.
That compressor generates heat as a byproduct of its operation. In a window air conditioner, this heat vents outside through the back of the unit. In a dehumidifier, there is nowhere for it to go, so it stays in the room. The result is air that is drier but warmer than when it entered the machine.
The temperature rise is usually small — often 1 to 3 degrees Fahrenheit — but it is real. In a small, sealed bedroom, running a dehumidifier continuously can noticeably warm the space over several hours.
When lower humidity actually improves comfort
Humidity affects how your body cools itself. When the air is saturated with moisture, sweat cannot evaporate from your skin, so your body stays hot even if the temperature is moderate. At 50% humidity and 75°F, you feel reasonably comfortable. At 80% humidity and 75°F, you feel clammy and overheated.
A dehumidifier addresses this by lowering the humidity level. Bringing a room from 75% humidity down to 45% humidity at the same 75°F temperature will make the space feel significantly more pleasant. You will not be cool, but you will stop feeling sticky.
This effect is strongest in basements, bathrooms, and other naturally damp spaces where cooling is not the main issue. If your room is already at a comfortable temperature but feels muggy, a dehumidifier solves the problem. If your room is hot, a dehumidifier will make it feel worse because it adds heat while removing moisture.
Dehumidifiers versus air conditioners for cooling
An air conditioner removes both heat and moisture. It pulls warm, humid air across cold coils, water condenses away, and the cooled, dry air returns to the room. The heat the compressor generates is vented outside through a window unit or outdoor condenser, so it does not warm your living space.
A dehumidifier removes only moisture. The heat stays in the room. If your goal is to lower the actual temperature, an air conditioner is the only tool that works. A dehumidifier is useful only when the temperature is already acceptable but the air is too damp.
Some portable air conditioners are marketed as "two-in-one" cooling and dehumidifying units. These are true air conditioners with a hose that vents heat outside. They are not dehumidifiers with added cooling; the distinction matters because the heat venting makes them effective at lowering room temperature.
How to use a dehumidifier without warming your room
To minimize the heat a dehumidifier adds, run it in a space that is already cool or well-ventilated. A basement at 68°F with 80% humidity is an ideal use case — the dehumidifier will lower humidity without the slight temperature rise being noticeable. A bedroom at 78°F with high humidity is a poor use case because the added heat will make the room feel worse.
Ventilation also matters. If you can open a window or door to allow air circulation, the heat the dehumidifier produces will disperse instead of accumulating. In a sealed room, the warmth builds up over time. In a room with air movement, the effect is much smaller.
Size also affects the outcome. A dehumidifier rated for 5,000 square feet running in a 200-square-foot bedroom will cycle on and off frequently, producing less continuous heat. An undersized unit that runs constantly will warm the room more noticeably.
Signs your room needs a dehumidifier instead of a cooler
A dehumidifier is the right choice if your room temperature is already comfortable but you notice condensation on windows, a musty smell, or visible mold spots. These are signs of excess moisture, not heat. Lowering the humidity will solve the problem.
You should consider an air conditioner instead if the room feels hot, the temperature is above your comfort range, or you sweat even when sitting still. A dehumidifier will not help in these cases and may make things worse.
Some spaces need both tools. A basement that is cool but damp benefits from a dehumidifier. A basement that is both hot and damp needs an air conditioner, which handles both problems at once.
Energy cost of running a dehumidifier
A typical dehumidifier uses 300 to 700 watts, depending on size and model. Running one continuously costs roughly $20 to $50 per month in electricity, though this varies by your local power rates and the unit's efficiency rating.
Because a dehumidifier produces heat, running it in a sealed room may force your air conditioner to work harder to maintain your target temperature. This can offset some of the dehumidifier's benefit and increase your total cooling bill. In a naturally cool space or a well-ventilated room, this is not a concern.
An Energy Star-rated dehumidifier uses less electricity than a standard model for the same moisture removal. If you plan to run the unit frequently, the higher upfront cost of an efficient model usually pays back within a year or two.
Frequently Asked Questions
Can I use a dehumidifier to cool my bedroom at night?
No. A dehumidifier will not lower the room temperature and may actually warm it slightly. If your bedroom is hot, you need an air conditioner or a fan. A dehumidifier is useful only if the room is already cool enough but feels damp or muggy.
Will a dehumidifier help if my room is hot and humid?
It will make the humidity lower but the heat worse. The dehumidifier removes moisture, which improves comfort slightly, but it also adds heat from the compressor, which makes the room warmer overall. An air conditioner solves both problems at once.
Does a dehumidifier use a lot of electricity?
A typical dehumidifier uses 300 to 700 watts and costs roughly $20 to $50 per month to run continuously, depending on the model and your local electricity rates. An Energy Star unit is more efficient and costs less to operate over time.
What is the difference between a dehumidifier and a portable air conditioner?
A dehumidifier removes moisture but keeps heat in the room. A portable air conditioner removes both heat and moisture by venting the heat outside through a window hose. If you want to lower the actual temperature, you need an air conditioner, not a dehumidifier.
Should I run my dehumidifier with windows open or closed?
Closed windows trap the heat the dehumidifier produces, warming the room over time. Open windows or doors allow that heat to escape. If your goal is comfort, running the dehumidifier with some ventilation is more effective than sealing the room.