How Much Does It Cost to Run a Dehumidifier?

Dehumidifiers range from about 150 W for a small compressor model to over 500 W for a large one. EcoAir's 12-litre-a-day compressor unit draws 156–180 W, LG's 21-litre Korean model 336 W and LG's 50-pint (about 23-litre) US model 545 W.

We use 300 W as a typical figure. At 8 hours a day that's 2.4 kWh: about $0.44 a day in the US, £0.63 in the UK and €0.87 in Germany. Over a month it comes to about 73 kWh.

A dehumidifier with a humidistat switches off once the air reaches the humidity you set, so in a fairly dry room it runs only part of the time. In a damp basement in a humid summer, it may run most of the day. LG's own running-cost example for its Korean model assumes 5.7 hours a day.

Compressor (refrigerant) dehumidifiers pull air over a cold coil, where moisture condenses and drips into the tank. They work best in warm, humid rooms. EcoAir rates its compressor model for 15–35°C, and ENERGY STAR notes that frost can form on the coils below about 65°F (18°C).

Desiccant dehumidifiers soak up moisture in a material such as zeolite, which a heater then dries out. They keep working in cold rooms, but the heater makes them use more power: EcoAir's 7.5-litre desiccant model draws 300 W on low and 580 W on high.

Per litre removed, desiccant models usually cost more. Panasonic's Japanese desiccant model removes 5.4 litres a day at 285 W, while its newer hybrid model removes 12.5 litres a day at 225 W. Panasonic's previous hybrid, which used a heater, drew 715 W.

Japanese brands also sell hybrid models that combine both methods, so they work well in both summer and winter.

Many people use a dehumidifier to dry laundry indoors: in the UK and Ireland mostly in winter, and in Japan and Korea during the rainy season in June and July.

It's much cheaper than a tumble dryer. Panasonic rates its newer hybrid at about 312 Wh to dry about 2 kg of laundry in 90 minutes outside winter, and 423 Wh in winter. A typical electric tumble dryer uses about 2.4 kWh a load.

In the US, dehumidifiers are a fixture of damp basements in summer. ENERGY STAR says the best indoor humidity is generally 30–50%, and that certified models are 20% more efficient than non-certified ones.

Damp seasons differ by place: roughly June to September in Japan, Korea and much of the US, and the colder months in the UK, Ireland, Australia and New Zealand, when condensation and mould are worst.

Capacities are rated under test conditions that differ by country, for example 27°C and 60% humidity in Japan and 65°F (18°C) in the US since 2019. Your unit's exact power is on its label or spec sheet; use that number in the calculator.

• Set the humidistat to the level you need instead of running flat out. ENERGY STAR suggests 30–50% indoor humidity, and 30–40% in the heating season to prevent window condensation.
• Close the doors and windows of the room you're drying.
• Choose a compressor model for warm rooms, and a desiccant model for cold garages, boats or unheated rooms.
• For laundry, put the dehumidifier in a small closed room with the clothes spread out.
• Clean the filter regularly, and use a drain hose if the unit runs for long periods.
• When buying, compare litres removed per kWh (the Integrated Energy Factor in the US) and choose an ENERGY STAR or high-efficiency model.

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