Dehumidifier running cost

How a dehumidifier uses electricity

A compressor dehumidifier draws air over a cold coil, where moisture condenses and is collected, then passes the air back into the room. Most of its electricity goes to the compressor and the fan. Its built-in humidistat switches the compressor on and off: ENERGY STAR explains that once the room reaches the humidity you set, the dehumidifier cycles on and off automatically to keep it there. So a dehumidifier that is switched on for 8 hours does not necessarily draw its rated power for all 8 hours.

How the estimate works

• Energy per day of use (kWh) = rated power (W) × effective power (%) ÷ 100 × hours switched on ÷ 1,000.
• Week = the daily figure × days of use per week. Year = week × 365 ÷ 7. Average month = year ÷ 12.
• Cost = energy (kWh) × your price per kWh.

Effective power is the share of the switched-on time that the dehumidifier runs at its rated power. The calculator starts at 100%, which assumes it never cycles off: an upper estimate. Lower it only if you have a reason, such as a reading from a plug-in energy monitor. No typical percentage is suggested, because it depends on how damp the room is, the humidity you set, the temperature and the size of the space.

Where to find the rated power

• The rating plate on the back or underside of the unit, or the manual, usually gives the power in watts (W).
• If the plate gives only volts and amps, the volts and amps helper on the kWh calculator turns them into power. Without a power factor the result is an upper estimate.
• The capacity in litres or pints per day is how much water it can remove, not its power, so do not enter it as watts.
• A plug-in energy monitor measures what your unit actually uses over a day, including the time the compressor is off; see how to measure real appliance electricity use. Divide the measured kWh by the rated power × hours switched on ÷ 1,000 to work out an effective power percentage.

Example (illustrative only)

A dehumidifier rated at 500 W, switched on 8 hours a day, 7 days a week, with the compressor running 60% of that time, priced at $0.20 per kWh. The 500 W, 60% and $0.20 are example figures, not a typical model, duty cycle or current average price, so enter your own.

• Per day: 500 × 60% × 8 ÷ 1,000 = 2.4 kWh, costing $0.48.
• Week: 2.4 kWh × 7 = 16.8 kWh, costing $3.36.
• Average month: 876 kWh ÷ 12 = 73 kWh, costing $14.60.
• Year: 16.8 kWh × 365 ÷ 7 = 876 kWh, costing $175.20.

At 100% effective power, the same unit would use 4 kWh a day. That is the upper end of the estimate. If you only run it in damp months, multiply the weekly cost by the weeks you use it.

What changes how long it runs

• The humidity setting. A lower target keeps the compressor running for longer. ENERGY STAR says the optimum relative humidity for a building is generally considered to be between 30% and 50%.
• How much moisture there is. A damp basement, drying laundry or a recent leak means more water to remove and more running time.
• Temperature. In a cold room, frost can form on the coil. ENERGY STAR notes this can make the compressor cycle on and off repeatedly without removing moisture, which uses electricity without drying the room.
• Doors and windows. Damp air coming in from outside or from other rooms adds to the moisture the unit has to remove.

Comparing models

ENERGY STAR measures dehumidifier efficiency by the Integrated Energy Factor, in litres of water removed per kWh. A higher figure means a more efficient dehumidifier, and ENERGY STAR says certified models are 20% more efficient than non-certified ones. The factor comes from a standard test, so use it to compare models rather than to work out your own running cost.

Reading your result

• The result is an estimate for the inputs you entered, not a measurement or a bill.
• With 100% effective power it is an upper estimate; the real figure is lower whenever the compressor cycles off.
• The month and year assume the same use every week of the year.
• Your bill also includes other appliances, fixed charges and taxes. See the disclaimer.

The methodology explains every formula and rounding rule. For a heater or an air conditioner, use the space heater or air conditioner calculator.

Sources

These sources support specific statements on this page. They do not review or endorse this calculator or its results. Last reviewed 1 November 2026.

• ENERGY STAR: Dehumidifiers. Built-in humidistat and on/off cycling, the 30% to 50% humidity range, frost and compressor cycling, the Integrated Energy Factor in L/kWh and the 20% efficiency difference.
• U.S. Energy Information Administration (EIA): Measuring electricity. A watthour is one watt for one hour; a kilowatt is 1,000 watts.