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 dried air returns to the room at roughly the same temperature it entered — sometimes even slightly warmer, because the motor and compressor generate a small amount of heat.
However, a room that feels uncomfortably sticky often feels warmer than it actually is. When humidity is high, sweat on your skin cannot evaporate, and your body's cooling system fails. Removing that moisture can make 78 degrees feel like 72 degrees, even though the thermometer has not moved. That sensation of relief is real, but it is not the same as lowering the room temperature.
If your goal is to lower the actual temperature, you need air conditioning or a fan that moves outside air into the space. A dehumidifier alone will not do that.
Key Takeaways
- Dehumidifiers remove water from the air but do not lower room temperature; they may even raise it slightly because the compressor generates heat.
- High humidity makes a room feel warmer than it is because sweat cannot evaporate from your skin, so removing moisture can improve comfort without changing the actual temperature.
- If you need to lower the actual temperature, use air conditioning or a window fan that brings in outside air; a dehumidifier is not a substitute.
- Running a dehumidifier in a sealed room with no outside air source will not cool the space and may slightly increase temperature over time.
Why humidity makes you feel hot
Your body cools itself by sweating and then evaporating that sweat through your skin. When the air is already saturated with moisture, evaporation slows or stops. Sweat stays on your skin instead of disappearing, and your body temperature stays high even though the room is not actually hot.
This is why a humid 75-degree room feels stifling, while a dry 75-degree room feels comfortable. The temperature is identical, but the humidity level changes how your body can shed heat. Removing that humidity restores the evaporation process and makes you feel cooler — but the thermometer will still read 75 degrees.
What a dehumidifier actually does to room temperature
A dehumidifier cools air slightly as it passes over the evaporator coils inside the machine. That cold coil is where water condenses out of the air. But then the dried air is warmed again as it passes over the condenser coils on the back of the unit — the part that gets hot — before it returns to the room.
In most dehumidifiers, these two temperature changes nearly cancel each other out. The air that comes back into the room is roughly the same temperature as when it entered, or sometimes a fraction of a degree warmer. Over a full day of running, the motor and compressor add enough waste heat that the room temperature may actually rise by one or two degrees, especially in a small, sealed space.
This is why dehumidifiers are not air conditioners. An air conditioner removes heat from the room and sends it outside through a duct or window unit. A dehumidifier removes water and keeps the heat inside.
When a dehumidifier helps with comfort
A dehumidifier is most useful in damp basements, bathrooms after showers, or bedrooms in humid climates where the actual temperature is acceptable but the moisture level is not. If your room is 72 degrees and 80 percent humidity, a dehumidifier will bring that down to 50 or 60 percent humidity, and you will feel noticeably more comfortable — cooler, less clammy, easier to sleep.
It is also useful alongside air conditioning. If your AC is running but the room still feels sticky, the AC may not be removing humidity fast enough. Running a dehumidifier at the same time speeds up moisture removal and improves comfort without lowering the thermostat further.
A dehumidifier does not help if the room is already too hot. If it is 85 degrees and humid, removing the humidity will make the heat feel less oppressive, but you will still be too warm. You need to lower the actual temperature with AC or a fan bringing in cooler outside air.
Dehumidifiers versus fans and air conditioning
A fan moves air around but does not remove heat or moisture. It can make you feel cooler by increasing evaporation from your skin, but the room temperature stays the same. A fan uses far less electricity than a dehumidifier and is useful if humidity is not the problem.
A window fan or portable AC unit that exhausts to the outside can bring in cooler air from outside and lower the actual room temperature. This works only if the outside air is cooler than the inside air, which is why it is most effective at night or in cooler climates.
Air conditioning removes both heat and moisture and is the only option that will reliably lower room temperature. Central AC, window units, and portable AC units all work by moving heat outside the room. They are more expensive to run than a dehumidifier but are the only choice if the room is genuinely too hot.
How to know if you need a dehumidifier or a cooler
Check the actual room temperature with a thermometer. If it is above 78 degrees and you want it lower, you need cooling — a fan or air conditioner. A dehumidifier will not help.
If the temperature is acceptable but the room feels clammy, sticky, or smells musty, humidity is the problem. A dehumidifier will help. You can also check humidity with an inexpensive hygrometer, a small device that displays both temperature and humidity percentage. Comfortable humidity is usually between 30 and 50 percent. Above 60 percent, most people notice dampness.
If the temperature is too high and the humidity is also high, you need both cooling and dehumidification. Start with air conditioning, which removes both. If AC alone does not bring humidity down fast enough, add a dehumidifier.
Running costs and efficiency
A typical dehumidifier uses 300 to 700 watts, depending on size and how hard it is working. Running one continuously costs roughly $20 to $50 per month in electricity, depending on your local rates. A window air conditioner uses 500 to 1,500 watts and costs $30 to $100 per month.
Because a dehumidifier does not lower temperature, it is cheaper to run than AC if humidity is your only concern. But if you need both lower temperature and lower humidity, running AC alone is usually more efficient than running AC plus a dehumidifier, because AC does both jobs at once.
Frequently Asked Questions
Can I use a dehumidifier instead of air conditioning?
No. A dehumidifier removes moisture but does not lower room temperature. If the room is too hot, you need air conditioning or a fan bringing in outside air. A dehumidifier will make you feel slightly more comfortable by reducing humidity, but the thermometer will not change.
Will a dehumidifier make my room feel cooler?
Yes, it may feel cooler because removing humidity allows sweat to evaporate from your skin more easily. But the actual air temperature does not drop. If the room is 78 degrees and humid, it might feel like 74 degrees after dehumidifying, but it is still 78 degrees.
Does a dehumidifier use a lot of electricity?
A dehumidifier typically uses 300 to 700 watts and costs $20 to $50 per month to run continuously. That is less than air conditioning, but more than a fan. The exact cost depends on the machine size, how often it runs, and your local electricity rates.
What is the difference between a dehumidifier and a portable air conditioner?
A dehumidifier removes moisture only. A portable air conditioner removes both heat and moisture and exhausts hot air outside through a hose or duct. If you need to lower room temperature, a portable AC is the right choice. If you only need to reduce humidity, a dehumidifier is cheaper to run.
Should I run a dehumidifier with my air conditioner?
Usually not necessary. Air conditioning removes both heat and moisture, so it handles both jobs. Run a dehumidifier alongside AC only if the room still feels damp after AC has been running for several hours, which suggests the AC is not removing humidity fast enough.