What does a dehumidifier cost to run?
Less than people fear, and often less than the heating you would otherwise use to dry a room out.
Typical model is rated 300W
Price cap is 26.11p
8p per hour, 1,080 hours a year, 324 kWh in total — about £7 a month. Costed over 180 days, not the whole year — this is a winter appliance.
A typical 10–12 litre compressor dehumidifier draws around 300W when the compressor is running, and rather less on standby between cycles. Running it six hours a day through the winter is a genuine cost, but a small one next to the heating.
The reason it can save money is indirect: dry air feels warmer than damp air at the same temperature, and drying laundry indoors without ventilation is what puts the moisture there in the first place. Pulling that water out with a dehumidifier is far cheaper than raising the temperature of the whole room until it evaporates on its own.
One caveat that catches people out in a cold house: compressor models lose efficiency below about 15°C, which is exactly when an unheated bedroom or garage needs them. In a genuinely cold space a desiccant model works better, though it draws more power.
The short answer: A few pence an hour. Cheaper than heating a damp room, and much cheaper than fixing damp walls.
What actually helps
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This is the small stuff
Every appliance on this site put together is usually less than a third of a typical energy bill. Heating the house is the rest of it. If the numbers here bothered you, the number that actually matters is what your heating costs — and whether a heat pump would make it better or worse in your particular house.
Work out your heating costOther appliances
Energy figures checked 2026-08-26. Electricity priced at the Ofgem cap for 1 July – 30 September 2026. Your own machine and tariff will differ — put your figures in above.