A dehumidifier will not lower the actual temperature, but it can make a room feel cooler

A dehumidifier removes moisture from the air, not heat. Your thermometer will show almost no change—maybe a degree or two at most. But your skin will feel cooler because sweat evaporates more easily when humidity is lower, and that sensation of coolness is real, even though the air temperature itself has not dropped.

If you are hoping a dehumidifier will replace an air conditioner or let you turn off your AC to save money, it will not work that way. A dehumidifier uses electricity to run and actually generates a small amount of heat as a byproduct. In a sealed room, it may even raise the temperature slightly over time. What it does do is make existing cool air feel more comfortable on your skin.

Key Takeaways

  • A dehumidifier removes water from the air but does not lower room temperature; it makes the air feel cooler because sweat evaporates faster in dry conditions.
  • Dehumidifiers generate heat as they run, so they may slightly raise room temperature while making it feel more comfortable.
  • In a humid climate, running a dehumidifier alongside your air conditioner lets you set the AC to a higher temperature and still feel comfortable, which can reduce cooling costs.
  • A dehumidifier works best in rooms where humidity is above 50 percent; below that level, it provides little benefit and wastes electricity.
  • If your goal is to lower actual room temperature, an air conditioner, fan, or better ventilation will work; a dehumidifier alone will not.

Why humidity makes a room feel hotter than it is

Your body cools itself by sweating and then letting that sweat evaporate from your skin. When the air is dry, sweat evaporates quickly and you feel cooler. When the air is humid, sweat cannot evaporate as easily because the air is already full of water vapor. Your skin stays wet, heat stays trapped against your body, and you feel much hotter than the thermometer says you should.

This is why a room at 75 degrees and 70 percent humidity feels uncomfortable, while a room at 75 degrees and 40 percent humidity feels pleasant. The temperature is the same, but the humidity changes how your body can shed heat. A dehumidifier addresses only the humidity side of that equation.

How a dehumidifier actually affects room temperature

A dehumidifier pulls air across cold coils inside the unit. Water condenses on those coils and drips into a tank or drain line. The dried air then passes over the warm compressor and back into the room. That warm air is slightly warmer than the air that went in, so the dehumidifier actually adds a small amount of heat to the room as it runs.

In most cases, the temperature rise is small—often less than one degree in a typical bedroom. But in a small, sealed space like a bathroom or closet, or if you run the dehumidifier for many hours, the effect becomes noticeable. This is why dehumidifiers are most useful in naturally cool spaces or alongside air conditioning, not as a replacement for it.

When a dehumidifier can reduce your cooling costs

If you live in a humid climate and run air conditioning, a dehumidifier can help you use less energy. Here is how: your air conditioner has to remove both heat and moisture from the air. When you run a dehumidifier in the same space, it removes the moisture first. Your AC then does not have to work as hard to reach the same comfort level, so you can set the thermostat a few degrees higher and still feel comfortable.

For example, if you normally set your AC to 72 degrees in humid conditions, running a dehumidifier might let you set it to 75 degrees and feel the same level of comfort. That three-degree difference can lower your cooling bill by 10 to 15 percent, depending on your climate and how long you run the system. The key is that the dehumidifier and AC work together, not that the dehumidifier replaces the AC.

Signs your room has too much humidity

Humidity above 50 percent is where most people start to feel uncomfortable. Above 60 percent, you may notice condensation on windows, a clammy feeling in the air, or a musty smell. Mold and dust mites thrive above 60 percent humidity, so controlling moisture also protects your home and health.

You can measure humidity with an inexpensive digital hygrometer, which costs $10 to $30 and shows both temperature and humidity on a small display. If your humidity is consistently above 50 percent, a dehumidifier will make the room feel noticeably better. If it is below 40 percent, running a dehumidifier wastes electricity and may make the air uncomfortably dry.

Better ways to actually cool a room

If your goal is to lower the actual temperature, not just make it feel cooler, a dehumidifier alone will not do it. An air conditioner removes both heat and moisture, so it is the only appliance that will lower the thermometer reading. A ceiling fan or portable fan does not lower temperature either, but it moves air across your skin, which makes you feel cooler—similar to how a dehumidifier works, but without using as much electricity.

Opening windows at night when outdoor temperature is lower than indoor temperature, closing blinds during the day to block sunlight, and improving ventilation are all free or low-cost ways to reduce room temperature. In dry climates, an evaporative cooler (also called a swamp cooler) can lower temperature while also adding moisture, which is the opposite of what a dehumidifier does.

Dehumidifier placement and settings for best results

Place a dehumidifier in the center of the room or in the area where humidity is highest, not in a corner or against a wall. The unit pulls air in from one side and pushes it out the other, so it needs space to work. Close doors and windows to keep the humid air from outside from entering while the dehumidifier runs.

Most dehumidifiers have a humidity setting—you dial in a target level (usually 40 to 50 percent) and the unit turns on and off automatically to maintain it. This is more efficient than running it continuously. Empty the water tank regularly, or connect a drain hose to a floor drain or window so you do not have to empty it by hand. Check the filter monthly and clean or replace it as needed so the unit does not lose suction.

Frequently Asked Questions

Can I use a dehumidifier instead of air conditioning?

No. A dehumidifier removes moisture but does not lower temperature and may even raise it slightly. An air conditioner is the only appliance that removes heat from a room. You can use a dehumidifier alongside AC to reduce how hard the AC has to work, but not as a replacement.

Will a dehumidifier help if my room is already cool but feels clammy?

Yes. If the temperature is comfortable but humidity is high, a dehumidifier will make the room feel much better without raising the temperature. This is common in basements or in humid climates where AC is running but moisture is still present.

How much does it cost to run a dehumidifier?

A typical dehumidifier uses 300 to 700 watts. Running one 24 hours a day costs roughly $3 to $7 per month, depending on your local electricity rate. Running it only when humidity is above 50 percent costs less.

Should I run a dehumidifier and air conditioner at the same time?

Yes, if humidity is high. The dehumidifier removes moisture so your AC does not have to work as hard, which can lower your overall energy use. Make sure the dehumidifier drain does not back up into the AC condensate line.

What humidity level should I aim for?

Between 30 and 50 percent is ideal for comfort and health. Below 30 percent, the air feels dry and can irritate your skin and sinuses. Above 50 percent, you start to feel clammy and mold begins to grow.