How much energy does a dehumidifier use? Get your own answer: enter your wattage, hours of use per day and electricity rate, and press Calculate to see your cost per day, month and year. Those same results also cover how much electricity a dehumidifier uses.
Wondering how much energy does a dehumidifier use before you plug one in? Most home units draw between 250 and 750 watts, which works out to roughly $11 to $30 a month on your electricity bill when the machine runs eight hours a day. Below you'll find the numbers behind that range, how to calculate your own cost, and what makes a damp, musty room cheaper or pricier to dry out.
A dehumidifier's power consumption is printed on its rating plate in watts, and that single number drives everything else. A small closet unit may pull under 300 watts, while a large basement model can pull more than 700. Because the machine only draws that full load while the compressor or heater is actually running, your real energy consumption depends on how many hours it works each day, not on the hours it spends plugged in. Try more appliances in our appliance energy cost calculator.
The simplest way to think about it: a dehumidifier is a small appliance with a steady appetite, similar to a large fridge when it is running. It does not spike like a hair dryer, but it can run for many hours in a row during humid weather, and that is where the dehumidifier running costs add up.
Capacity is quoted in pints of moisture removed per 24 hours, and bigger units draw more power. The table below uses typical rating-plate figures for compressor models, an assumed run time of eight hours a day, and a flat electricity price of $0.17 per kWh. Your own rate and run time will move every number up or down in proportion.
| Unit size | Typical watts | kWh per day (8 hours) | kWh per month | Monthly cost at $0.17 |
|---|---|---|---|---|
| 22 pints | 270 W | 2.16 | 64.8 | $11.02 |
| 35 pints | 380 W | 3.04 | 91.2 | $15.50 |
| 50 pints | 560 W | 4.48 | 134.4 | $22.85 |
| 70 pints | 740 W | 5.92 | 177.6 | $30.19 |
Watts measure how fast an appliance draws power at one instant. Watt-hours measure how much it draws over time, and your utility bills you in kWh, which is 1,000 watt-hours. To turn a rating plate into a daily figure, multiply watts by the hours of operation and divide by 1,000:
$$\text{kWh per day} = \frac{\text{watts} \times \text{hours}}{1000}$$Then multiply by your tariff to get the cost:
$$\text{cost} = \text{kWh} \times \text{price per kWh}$$For a 560-watt unit running 8 hours, that is \(560 \times 8 \div 1000 = 4.48\) kWh, or about $0.76 a day at $0.17 per kWh.
Take a 50-pint compressor dehumidifier rated at 560 watts, placed in a damp finished basement, with electricity at $0.17 per kWh. The numbers below are the same ones used in the table above, so you can follow the arithmetic step by step.
Running 8 hours a day uses 4.48 kWh. Over a 30-day month that is 134.4 kWh, which costs $22.85. In other words, the unit adds about 76 cents a day to your energy bill, a small line item compared with heating or cooling a whole house.
If the same machine ran for all 24 hours every day, it would use 13.44 kWh a day, 403.2 kWh a month and cost about $68.54. That is roughly three times the figure above, and it is the upper limit for this model, because a unit that is holding your target humidity does not actually run the compressor continuously. Once the room reaches the setpoint, it cycles off and only draws a trickle of power for its controls.
The technology inside the box changes both the wattage and the conditions where the machine is efficient. The two main designs, plus a hybrid, work very differently.
A compressor dehumidifier works like a small air conditioner. A fan pulls room air across cold coils chilled by a refrigerant loop, so water vapour turns to liquid through condensation and drips into the tank. The dry air is then warmed slightly as it passes back over the hot side of the loop. This design removes the most water for each unit of electricity when a room is warm and humid, which is why it is the usual choice for living rooms and basements in summer.
A desiccant dehumidifier has no cold coils. A slowly turning wheel of desiccant material, typically silica gel, soaks up moisture, and an electric heater then dries the wheel out so it can keep working. That heater is the main energy cost, so these models often draw 300 to 700 watts for a modest pint capacity. In exchange, a desiccant unit stays effective in cold garages and sheds where a compressor model would ice up, and it is lighter in weight and lower in noise.
Hybrid dehumidifiers combine both methods and switch between them depending on the temperature and humidity. They are less common and cost more up front, but they can hold a steadier water removal rate across the seasons.
Because two machines with the same pint capacity can differ a lot in wattage, an energy efficiency label is the quickest way to compare them. Look for the label before you buy, not after you see the first bill.
A good energy efficiency rating is based on how much water extracted per kWh of electricity, expressed in liters per kWh. Testing under the ANSI/AHAM method, which uses a 26.7°C (80°F), 60% relative humidity room, gives an objective extraction rate that is closer to everyday conditions than the manufacturer's headline pint figure. Energy Star models need about 1.6 liters per kWh or better in the smaller sizes. You can flip the same figure into a cost per litre: divide your kWh price by the liters extracted per kWh, and the lowest result wins.
Matching dehumidification capacity to the space matters as much as the label. A rough guide is up to 30 pints for closets and bathrooms, 30 to 50 pints for bedrooms and living rooms, and 50 to 70 pints for basements, expressed in square feet as roughly 500 square feet for a 35-pint unit and 1,500 for a 70-pint model. An undersized unit runs flat out and never reaches its target, while an oversized one cycles quickly and wastes little. Check the water tank size too: a small tank on a big machine means constant emptying or a shut-off before the room is dry.
The wattage on the plate is a ceiling, not a forecast. Four things decide how close to that ceiling you get.
A compressor model pulls more water per kWh in warm air, so a 24°C room with 70% relative humidity is cheap to dry, while a 10°C cellar is not. When the temperature falls, coils frost over and the unit spends energy on defrost cycles instead of removing moisture. Your target also matters: asking for 40% instead of 50% keeps the unit running far longer because each point of humidity removed takes more work than the last.
The control system decides when the machine runs, and a poor one wastes power. A manual dehumidifier runs until you switch it off, so pair it with a hygrometer and revisit the settings each season. An automatic dehumidifier with a built-in humidistat senses the air and shuts the compressor off at the target. A smart dehumidifier goes a step further by logging readings and learning your home's pattern. Models with inverter motors, or inverter technology, adjust their speed instead of switching hard on and off, and drop to standby when the room is comfortable.
A leaky basement or cellar keeps feeding moisture back into the air, so the unit never gets to rest. Drying laundry indoors does the same, and many machines have a laundry setting that runs the fan faster and draws more power. Closing doors and keeping humid air from creeping in from other rooms lowers your humidity levels workload.
An air conditioner also removes humidity, because warm indoor air passing over its evaporator coils loses moisture as it cools. But it is built to cool, and a typical window air conditioner draws 500 to 1,500 watts, often well above a portable dehumidifier of the same price class. When humidity is the only problem, such as on a mild, sticky day, the dehumidifier is cheaper to run because it does not push cold air out.
On a hot day, the two work well together. A drier house feels cooler at the same thermostat reading, so your air conditioner can run less, which trims cooling costs and wear. A whole-house dehumidifier wired into the HVAC ductwork takes this further, handling moisture throughout the home, though it costs more to buy and install than a room unit. If you need only one bedroom or one basement, a portable unit is usually the smarter buy for comfort per dollar.
Averages only go so far, so it is worth running the numbers for your own machine. You need three inputs: the wattage on the rating plate, the hours it actually runs, and the price per kWh on your latest statement.
As a second example, a 380-watt unit running 6 hours a day uses 2.28 kWh daily, or 68.4 kWh across a month. At $0.24 per kWh, a pricier regional rate, that dehumidifier costs $16.42 a month to run, so the same appliance can cost noticeably more or less purely because of where you live.
The rating plate describes the machine working flat out in warm, humid air. In practice the compressor switches off every time the room reaches your target, and a well-sealed room can stay there for hours. That cycling is why metered readings often land well below the textbook maths, and why the nameplate calculation is best treated as a safe upper estimate. If your bill jumps by far more than the formula predicts, look for a moisture source: an open crawl space, a dryer vented indoors, or a plumbing leak.
Put the unit in the open, at least a foot from walls and furniture, so the fan can pull air freely. Blocked intake grilles lower the extraction rate and stretch the run time. Keep interior doors closed in the room being dried, and empty or drain the tank before it fills so the unit never idles at full.
Small habits change how many hours the compressor runs. Start with these:
Rating plates give a maximum, not your real number. Plug the machine into a smart plug with energy monitoring for a week, read the kWh total, and multiply by your price. Many owners are surprised that the real figure is a fraction of the nameplate maths above, because the unit spends hours cycled off.
The cost is only half the picture. Excess moisture damages paint and wood, and persistent damp leads to mold, mildew and mould growth plus a musty smell that clings to clothes. Those spores can aggravate allergies and asthma, so keeping relative humidity between 30% and 50% supports better indoor air quality. Remediation or replacing warped flooring costs far more than $20 a month in power. You can also check garage door opener electricity consumption.
Cost also changes with the seasons. In summer the unit may run most of the day, perhaps 10 or more kWh across a long humid spell, while in winter cold air holds less water and the same machine may idle for most of the day and use a fraction of that. For the best use of your money, treat the roughly $23 monthly bills from the 50-pint example as an insurance premium against repairs. Pick a size that fits the room, set a sensible target, keep it maintained, and a dehumidifier will stay one of the cheapest appliances to run in your home.