A dehumidifier will not cool a room, but it may make the air feel more comfortable
A dehumidifier removes water from the air. It does not lower the temperature. If your room is 78 degrees and humid, a dehumidifier will keep it at 78 degrees but with less moisture — which can feel more pleasant, but the thermometer will not move.
The reason it might feel cooler is real, though. Humid air prevents sweat from evaporating off your skin, so your body cannot shed heat efficiently. When a dehumidifier pulls moisture out, sweat evaporates faster, and you feel cooler even though the air temperature has not changed. This effect is strongest in very humid conditions — above 60% relative humidity — and weakest when humidity is already moderate.
If you need the actual temperature to drop, you need air conditioning or a fan that moves air across your skin. A dehumidifier is a supplement to those tools, not a replacement.
Key Takeaways
- A dehumidifier removes moisture but does not lower air temperature; the room will stay the same degrees Fahrenheit.
- Lower humidity can make a room feel more comfortable because sweat evaporates faster, creating a cooling sensation on your skin.
- The comfort gain is most noticeable when humidity is very high (above 60%) and smallest when humidity is already moderate.
- An air conditioner or fan will cool or circulate air; a dehumidifier works best alongside one of those, not instead of one.
Why humidity makes you feel hot
Your body cools itself by sweating. When sweat evaporates, it pulls heat away from your skin. In dry air, sweat evaporates quickly and efficiently. In humid air, the air is already saturated with moisture, so sweat cannot evaporate as easily — it just sits on your skin, and your body stays hot.
This is why 78 degrees at 30% humidity feels comfortable, but 78 degrees at 80% humidity feels stifling. The temperature is identical. The difference is how well your body can shed heat. A dehumidifier speeds up evaporation by lowering the humidity, which helps your body work better — but it does not change the temperature itself.
What a dehumidifier actually does to comfort
In a very humid room — say, 75% relative humidity or higher — running a dehumidifier can make a noticeable difference in how the space feels. You will sweat less, your clothes will feel less clammy, and the air will not feel as thick. Many people report that they can lower their air conditioner a few degrees and still feel comfortable once humidity drops, which can reduce energy use.
In a moderately humid room — 50% to 60% — the comfort gain is smaller. The air already allows some evaporation, so removing more moisture helps but is not dramatic. In a dry room below 40% humidity, a dehumidifier will not improve comfort and may make it worse by drying out your skin and sinuses.
The key point: a dehumidifier makes existing cooling more effective. It does not create cooling on its own.
When to use a dehumidifier instead of lowering the thermostat
If your air conditioner is already running and the room still feels uncomfortable, a dehumidifier can help without forcing you to cool the entire house further. This is useful in basements, bathrooms, or bedrooms where moisture collects but the main air conditioner does not reach as well.
A dehumidifier also makes sense if you live in a humid climate and want to reduce air conditioning costs. By removing moisture, you can set your thermostat a degree or two higher and still feel comfortable — the dehumidifier does the work that would otherwise require the AC to run longer. Over a summer, this can add up to real savings on your electric bill.
However, if your room is hot and you have no air conditioning or fan, a dehumidifier alone will not solve the problem. You will still be hot; you will just be hot and less sweaty.
How dehumidifiers work and what they cost to run
A dehumidifier pulls air across cold coils, which condenses moisture out of it. The water drips into a tank or drain line, and the now-drier air is released back into the room. The process uses electricity — typically 300 to 700 watts for a mid-size unit, depending on the model and how hard it is working.
Running a dehumidifier 24 hours a day costs roughly $15 to $40 per month in electricity, depending on your local rates and the unit's efficiency. Most people run them only during the day or only when humidity is high, so the actual cost is usually lower. Some dehumidifiers have a humidistat that turns the unit on and off automatically when humidity rises above a set level, which reduces runtime and cost.
Dehumidifiers also generate heat as a byproduct of the condensation process. A unit that removes moisture will actually raise the room temperature slightly — usually 1 to 3 degrees. This is another reason they work best alongside air conditioning rather than as a replacement for it.
Dehumidifiers versus fans and air conditioning
A fan circulates air and helps sweat evaporate, which can make you feel cooler without lowering the temperature. A fan uses less electricity than a dehumidifier — typically 10 to 100 watts — and does not add heat to the room. If your main problem is stagnant air, a fan is cheaper and more effective than a dehumidifier.
An air conditioner lowers the actual temperature and also removes some moisture as a side effect. It is the most expensive option to run but the only one that actually cools the room. In a hot, humid climate, air conditioning is usually necessary for comfort; a dehumidifier can reduce how hard the AC has to work, but cannot replace it.
The best setup for a hot, humid room is usually air conditioning plus a fan for air movement. A dehumidifier can be added if humidity remains high even with the AC running, which sometimes happens in basements or poorly insulated rooms.
Signs your room is too humid and could benefit from a dehumidifier
If you notice condensation on windows, a musty smell, visible mold or mildew, or damp spots on walls or ceilings, humidity is too high. Relative humidity above 60% is generally considered uncomfortable and can promote mold growth. A dehumidifier can bring this down to a healthier range of 30% to 50%.
You can measure humidity with an inexpensive hygrometer, which costs $10 to $30 and displays the current relative humidity percentage. Many people find that once they see the number, they realize humidity is higher than they thought — especially in basements, bathrooms, and laundry rooms.
Frequently Asked Questions
Will a dehumidifier cool my room if I run it all night?
No. Running it longer will not lower the temperature. It will remove more moisture, which may make the room feel more comfortable, but the thermometer will stay the same. A dehumidifier also produces a small amount of heat as it operates, so very long runtimes can actually raise the room temperature slightly.
Can I use a dehumidifier instead of air conditioning?
Not if you need the room to be cooler. A dehumidifier only removes moisture; it does not lower temperature. If the room is hot, you need air conditioning or a fan to move air. A dehumidifier can work alongside AC to reduce how hard the unit has to work, but it cannot replace it.
Does a dehumidifier use a lot of electricity?
A mid-size dehumidifier uses 300 to 700 watts and costs roughly $15 to $40 per month to run continuously, depending on your local electricity rates. Most people run them only during humid seasons or only when humidity is high, so the actual cost is lower. A fan uses much less electricity — typically 10 to 100 watts.
What humidity level should I aim for?
Most experts recommend keeping relative humidity between 30% and 50%. Below 30%, the air becomes too dry and can irritate your skin and sinuses. Above 60%, mold and dust mites thrive, and the air feels uncomfortable. A hygrometer will show you the current level in your room.
Should I run a dehumidifier in winter?
Usually not. Winter air is naturally dry, especially indoors with heating running. Running a dehumidifier in winter will over-dry the air and waste electricity. Use it mainly during humid seasons — spring through fall in most climates, or year-round in very humid regions like the Southeast.