Key takeaways
- How much electricity does a dehumidifier use? Roughly 250 to 800 watts while running; see kWh math, monthly cost examples and ways to cut the bill.
Most home compressor dehumidifiers draw roughly 250 to 800 watts while the compressor is running, which works out to about 6 to 45 dollars a month at 17 cents per kWh, depending on size and how many hours it runs. The spread is wide because the electricity bill is set by two things the box rarely states: how efficient the unit is, and how long your particular room keeps it working.
This page works the arithmetic out in the open. The figures here are the Editorial team’s worked estimates, built from published specifications, manufacturer documentation and buyer reviews. They are not meter readings from a unit anyone here ran, and every example states its assumptions so you can replace them with your own.
Three numbers on one label: watts, amps and kWh
A dehumidifier’s nameplate usually lists volts and amps, such as 115 V and 5.2 A. Multiply them and you get volt-amperes, 598 in this example, or roughly 600. That is a ceiling, not an average. A running compressor typically draws less real power than the product of volts and amps, because of a quantity called the power factor, so the true wattage is commonly somewhat below the nameplate ceiling.
Watts measure the rate of using electricity at a moment. Your bill, however, charges for energy, measured in kilowatt-hours (kWh). One kWh is 1,000 watts sustained for one hour. So a 500 W machine running for 2 hours uses 1 kWh. The formula is simple: kWh equals watts divided by 1,000, multiplied by hours.
The second variable is the duty cycle: the share of time the compressor is actually on. A dehumidifier with a humidistat does not run constantly. It runs until the room reaches the target, rests, and restarts when humidity creeps up. In a mild, well-sealed room that might be 30 percent of the day. In a damp basement during a rainy week it might be 100 percent.
Put the three together and you have the working formula for this whole page: daily kWh equals running watts, divided by 1,000, times compressor hours per day. Multiply by your price per kWh to get dollars. Everything else, such as Energy Star labels, pint ratings and placement, is a way to change either the watts or the hours.
A practical tip: the label may show a maximum current for the whole appliance, including the fan and control board. The fan alone draws a small fraction of the total. When the compressor cycles off and the fan keeps running, the unit’s draw drops sharply, which is why a plug-in watt meter shows a jagged pattern rather than a flat line.
The pint rating measures water, not electricity
It is easy to assume a 50 pint dehumidifier uses more electricity than a 30 pint one. Often it does draw more watts, but the pint rating itself is an output figure: the amount of water the unit can remove per day under stated conditions. It says nothing directly about input power.
The link between the two is efficiency, usually expressed as liters of water removed per kilowatt-hour. A pint is about 0.473 liters, so a 50 pint per day rating equals roughly 23.7 liters a day. If a unit removes 2.0 liters per kWh, then pulling 23.7 liters costs about 11.8 kWh. Over 24 hours, that implies an average draw of about 490 W while working at full rated output. That is a hypothetical, but it shows how the three quantities connect.
Now compare two hypothetical units. Unit A is rated 35 pints and draws 400 W. Unit B is rated 50 pints and draws 550 W. Unit A’s efficiency works out to about 1.7 liters per kWh (16.6 liters a day divided by 9.6 kWh), and unit B’s to about 1.8 (23.7 divided by 13.2). The bigger unit draws 150 W more but is slightly more efficient per liter. If both are in a room that needs to shed 16 liters a day, unit B removes that water in about two-thirds of the time, so the larger machine can use similar or even less energy.
The lesson is that buying the smallest unit does not always minimize cost. An undersized machine in a damp room runs all day, never reaching the target, while an adequately sized one catches up and rests. Choosing capacity by the room’s dampness matters more than chasing the lowest wattage. If you are sizing for a compact space, our mobile home dehumidifier sizing guide shows how to match capacity to a smaller footprint.
What typical sizes draw: planning estimates
Specific wattage depends on the model, and the nameplate is the only reliable source. For planning, the table below uses assumed running watts for four common size classes. These are illustrative estimates for a typical compressor design, not values for any particular product.
| Size class | Assumed running watts | Assumed hours per day | kWh per day | kWh per 30 days | Cost per 30 days at 17 cents/kWh |
|---|---|---|---|---|---|
| Small, about 22 pints | 260 W | 8 | 2.08 | 62.4 | about 10.61 dollars |
| Medium, about 35 pints | 350 W | 8 | 2.80 | 84.0 | about 14.28 dollars |
| Large, about 50 pints | 500 W | 10 | 5.00 | 150.0 | about 25.50 dollars |
| Extra large, about 70 pints | 700 W | 12 | 8.40 | 252.0 | about 42.84 dollars |
Two features of the table are worth noting. First, the hours rise with the size class because bigger units tend to live in wetter spaces, such as basements, which keep them busy. Second, cost per pint of rating falls as size rises, which fits the idea that larger units are not simply proportionally worse.
Change a single assumption and the whole row moves. At 25 cents per kWh, the 50 pint row costs about 37.50 dollars; at 12 cents, about 18 dollars. Halve the hours and you halve the bill. Treat the table as a template: replace the watts with the number from your nameplate or watt meter, replace the hours with what you observe, and use the rate printed on your most recent utility statement.
Worked example one: a bedroom unit overnight
Take a 35 pint class unit in a bedroom of about 150 square feet on a humid coastal summer night. Assume it draws 300 W when the compressor runs, and the humidistat is set to 50 percent.
The unit runs eight hours overnight. At the start the room is at 62 percent, so the compressor works continuously for the first hour or two, then cycles, reaching a duty cycle of about 50 percent over the night. That means roughly four compressor hours. Energy: 0.3 kW times 4 hours is 1.2 kWh a night. Over 30 nights, that is 36 kWh. At 17 cents per kWh, the monthly cost is about 6.12 dollars.
Now the worst case for the same unit: it runs continuously for all eight hours, perhaps because the door is open to a damp hallway. That is 2.4 kWh a night, 72 kWh a month, and about 12.24 dollars. So a decision like closing the door is worth about 6 dollars a month in this example, which is the kind of small, steady difference that adds up over a season.
Add the fan and electronics. Even when the compressor is off, the fan may keep running in some modes and the display draws a few watts. As an estimate, adding 10 to 20 W for the fan across the whole eight hours is another 0.08 to 0.16 kWh a night, or about 40 to 80 cents a month. It is small but not zero.
A bedroom also raises a noise question. Running a unit overnight is only practical if the sound is tolerable, and quieter operation often means lower fan speed, which slightly lowers airflow and can lengthen run time. That is a trade-off between comfort and cost, and the right answer depends on how light a sleeper you are.
Worked example two: a wet basement, first week versus steady state
A basement shows the pattern better because the unit has a lot of work to do at first. Assume a 50 pint class unit drawing 500 W while the compressor runs. The basement starts the month at 72 percent relative humidity after a rainy stretch, and the target is 50 percent.
In week one, the unit runs nonstop. That is 24 hours at 0.5 kW, or 12 kWh a day, for 7 days: 84 kWh. The room dries down, the walls and stored items release their moisture, and humidity eventually falls toward the target.
For the remaining 23 days, assume a maintenance duty cycle of about 25 percent, or 6 compressor hours a day. That is 3 kWh a day, 69 kWh over 23 days. The month total is 153 kWh. At 17 cents per kWh, the bill impact is about 26.01 dollars, with roughly 55 percent of the energy spent in the first week.
That split is the most useful thing the example shows. The first week is a one-time cost of drying out a damp space, and it does not repeat unless something re-wets the basement. If the unit is still running 24 hours a day in week four, the extra electricity is a warning: either the unit is too small, the target is too low, or moisture is entering faster than the machine can remove it.
Compare the alternative: a unit at 50 percent duty for the whole month would use 0.5 kW times 12 hours times 30 days, which is 180 kWh and about 30.60 dollars. So a well-sealed basement settles into the cheaper pattern. The practical conclusion is to treat high run hours as a diagnostic, not a fixed cost.
Energy Star and efficiency: what the label means for your bill
Energy Star is a certification program. A dehumidifier that carries the label meets efficiency criteria for its capacity class, which means it removes more water per kWh than the baseline. The program publishes a list of certified products, and the key figure there is the energy factor in liters per kWh. Look at that number on the certified list, not just the badge, because the margin over the baseline varies by model and by class.
The dollar value of efficiency scales with run time. Suppose two 50 pint class units face the same demanding month, each needing to remove the full rated 23.7 liters a day (an extreme, wet-basement assumption). Unit X is at 1.6 liters per kWh and Unit Y at 2.0. Unit X needs 14.8 kWh a day and Unit Y 11.8 kWh. Over 30 days, that is about 444 kWh against 355 kWh, a gap of roughly 89 kWh, or about 15 dollars at 17 cents per kWh. For a unit that runs only a few weeks a year, the gap is much smaller.
So the label is worth most for machines that run a lot: a basement unit in a humid region, a crawlspace unit, a unit in a house with chronic moisture. For a bedroom unit that runs 4 hours a night, the savings are measured in a few dollars a season, and other features such as noise, drain options and tank size may matter more.
Two cautions. The certification does not make a unit quiet, nor does it guarantee it is the right size. And capacity ratings are quoted under specific temperature and humidity conditions, so compare the stated conditions when you compare two labels. A certified unit in a cold basement may still draw little and remove little.
Why the same dehumidifier costs different amounts in different homes
Two identical units can produce very different bills. The table below lists the factors that change the duty cycle or the efficiency, and what you can do about each.
| Factor | Effect on electricity use | What you can do |
|---|---|---|
| Room temperature | Cold air carries less moisture and chills the coil toward frosting, so output per kWh falls | Choose a model with auto defrost for cool rooms; do not expect full rated output below the rating temperature |
| Starting humidity | Higher humidity means more water to remove and more run time | Fix the moisture source first; expect a heavy first week |
| Target setting | A low target such as 40 percent keeps the compressor running longer | Aim for roughly 45 to 55 percent in most homes |
| Air leaks and open doors | Humid outside air replaces the dried air | Close doors and windows; seal gaps |
| Moisture sources | Dryers venting indoors, wet floors, plumbing leaks and uncovered dirt add water constantly | Vent dryers outdoors, fix leaks, cover dirt floors |
| Capacity versus load | An undersized unit runs nonstop; an oversized unit cycles briefly | Size to the dampest condition you expect |
One extra point on heat. Nearly all the electrical energy a dehumidifier uses ends up as heat in the room, because the compressor, fan and condensing coil all release it. A 500 W unit adds roughly 1,700 BTU per hour of heat, since a watt is about 3.41 BTU per hour. In winter that is a small side benefit; in a summer room with air conditioning, it adds to the cooling load, so part of the dehumidifier’s cost is the extra work for the cooling system.
Desiccant dehumidifiers, which use a drying wheel and a heater instead of a cold coil, have a different profile. They work well in cold spaces where compressor models struggle, but they generally use more electricity per liter at normal room temperatures and put out more heat. Check the unit type before comparing watts.
Ten ways to lower the bill
Most savings come from reducing the hours, not hunting for a lower wattage. In rough order of impact:
- Raise the target to 50 to 55 percent. Dropping from 40 to 55 percent can cut compressor hours substantially, though the exact savings depend on the room. Check the reading with a separate hygrometer.
- Stop the source. Vent the clothes dryer outdoors, fix dripping pipes, extend downspouts, and cover a dirt crawlspace floor with a vapor barrier. A dehumidifier fights symptoms, and cutting the source lowers the load.
- Close the space. Keep doors and windows shut while the unit runs and seal obvious gaps. A dehumidifier cannot dry the outdoors.
- Size correctly. An undersized unit runs nonstop. A modestly larger one reaches the target and rests.
- Use the humidistat, not continuous mode. Continuous mode ignores the target and keeps running.
- Give it airflow. Leave clearance around the intake and exhaust, and clean the filter every few weeks in the damp season. A clogged filter forces longer run time.
- Drain it automatically. A hose or pump prevents a full tank from stopping the unit while the room re-wets.
- Use schedules where rates vary. If your utility charges more at peak hours, a timer can concentrate drying in cheaper hours.
- Pick an efficient model for heavy use. For a unit that runs most of the summer, compare liters per kWh before buying.
- Turn it off when the season ends. If a room only gets damp in summer, there is no reason to run the unit in a dry winter.
Combined, the first four items can shift a basement unit from running 14 hours a day to 6, which in the 500 W example above would drop the monthly cost from about 35.70 dollars to about 15.30 dollars. That is a scenario, not a promise, but it shows which levers are large.
Measure your own unit with a plug-in watt meter
Estimates are useful for planning, and a meter is better for knowing. A plug-in watt meter sits between the wall outlet and the dehumidifier’s plug, costs little, and shows instantaneous watts and accumulated kWh. A step-by-step check takes a few days.
- Plug the meter into the outlet and the dehumidifier into the meter. If the unit has a heavy draw, check that the meter’s rating covers it.
- Note the running watts when the compressor is on. This is the number to use in the formulas above. It is usually steady within a modest range.
- Note the watts when only the fan runs, and the standby watts when the unit is idle but plugged in. These are typically much smaller.
- Leave the meter in place for at least three full days under normal conditions, then read the accumulated kWh and divide by the number of days.
- Multiply the daily kWh by 30 and by your price per kWh to get a monthly cost. Compare it with the estimate from the table.
If the numbers differ from the table, that is useful. A higher result than expected usually points to a long duty cycle, which in turn points to the factors above: a low target, an air leak or a moisture source. A lower one means the room is easier than assumed.
If you do not have a meter, the nameplate and the run-time method still work. Count how many hours a day the compressor is audibly on for a few days, then use the nameplate amps times volts as an upper bound for watts. The result will overstate the cost slightly, which is a safe error for budgeting.
Related guides
Frequently asked questions
How many watts does a dehumidifier use?
A typical home compressor dehumidifier draws somewhere around 250 to 800 watts while the compressor is running, depending on size. Small 20 to 35 pint units sit at the low end, and 50 to 70 pint units toward the middle and upper end. Those are planning estimates, not data for a specific model. The nameplate lists amps and volts, and multiplying them gives an upper bound that real running watts usually fall below.
How much does it cost to run a dehumidifier per month?
With assumed figures of 17 cents per kWh, a small bedroom unit running a few hours a day might cost about 6 to 15 dollars a month, while a 50 pint basement unit running 8 to 10 hours a day lands near 20 to 25 dollars. A big unit in a very wet space can reach 40 dollars or more. Your cost depends on your utility rate and on how many hours the compressor actually runs.
Does a bigger pint rating mean a higher electric bill?
Not directly. The pint rating measures water removed per day, which is output. Watts are input. A bigger unit usually draws more power while running, but it may reach your humidity target and shut off sooner, so total kWh can end up similar or even lower than an undersized unit running nonstop. Efficiency, measured in liters of water per kWh, tells you more about running cost than the pint number alone.
Is an Energy Star dehumidifier worth it?
It is worth considering when the unit will run many hours a year, because the savings accumulate with run time. A certified model removes more water per kWh than a typical uncertified one, but the savings in dollars depend on how big the efficiency gap is and how often the unit runs. In a damp basement running most of the summer, a more efficient model can repay a modest price premium. In an occasional-use room, it matters less.
Does a dehumidifier use power when the tank is full?
When the float switch trips, the compressor and fan normally stop, so the big draw ends. The control board and display may still draw a small standby load, typically a few watts as an estimate. A full tank also means the room is not being dried, so you pay for nothing. A drain hose or pump avoids this, keeping the unit working only when moisture needs removing.
