How much does it cost to run a dehumidifier 24 hours a day in the UK?

Heating By Ellen HartwellPublished 26 September 2026

What a dehumidifier actually draws

The number on the box is rarely the number the machine pulls from the wall, because a compressor dehumidifier works harder in cold damp air than in warm dry air. Meaco publishes measured figures for the Arete One 12L across four conditions, and the spread is wide enough to matter. At 20 degrees and 60 per cent relative humidity it draws 130 watts. Warm the room to 30 degrees at the same humidity and it goes to 151 watts. Drop the room to 10 degrees and push humidity to 80 per cent, the conditions you get in a cold bedroom with wet washing in it, and the draw rises to 186 watts. The worst case Meaco lists is 198 watts.

So when somebody tells you a dehumidifier costs 4p an hour, they are quoting the middle of that range and hoping your house matches. Ours does not, and neither does yours, which is why the calculator below lets you put in the figure from the plate on the back of your own machine.

The cost of a full 24 hours

Take the 151 watt figure as the everyday case. Running for a full day gives 151 watts divided by a thousand, multiplied by 24 hours, which is 3.62 kilowatt hours. At the Ofgem cap rate for the current period that comes to about 95p. At the top of the range, 198 watts, the same 24 hours costs £1.24. At the bottom, 130 watts in a warm dry room, it costs about 81p.

Those numbers assume the compressor runs continuously, and in practice it will not unless the room is genuinely soaking. Every modern machine has a humidistat, and once the air reaches the target the compressor stops and only the fan carries on, drawing a fraction of the power. A more honest picture for a typical British house in autumn is six hours of compressor time spread across the day, which is where the 24p figure in the quick answer comes from.

Rates: Ofgem cap 1 July to 30 September 2026 at 26.11p per kWh (source), EIA residential average June 2026 at 18.34 cents per kWh (source). Checked 2026-09-22.

Where the money actually goes

Two habits push a dehumidifier bill up far more than the model you chose.

The first is running it on continuous mode instead of a humidity target. Continuous mode tells the machine to ignore the humidistat and keep pulling water out forever, which is useful after a leak and wasteful the rest of the time. Set a target of 50 to 55 per cent and the machine does its own switching off.

The second is running it in a room with the door open. A dehumidifier dries the air it can reach, so if it can reach the whole house it will run all day and never hit target. Close the door, let it finish the room, then move it.

There is a third that costs nothing to fix. Compressor dehumidifiers lose efficiency below about 15 degrees because the coil ices up and the machine spends time defrosting itself rather than drying. If you are running one in an unheated garage or a cold conservatory through winter, a desiccant model will use more watts but get more water out per unit of electricity in those conditions.

Against a tumble dryer

The comparison people really want is drying washing. A vented or condenser tumble dryer pulls somewhere around 2.5 kilowatt hours for a 90 minute load, which is about 65p at the current cap rate. Putting the same load on an airer in a closed room with a dehumidifier running for five hours costs roughly 20p in electricity, so the dehumidifier wins clearly on cost.

It does not win on time, and it does not win on convenience. Five hours against ninety minutes is a real difference when you need school uniform dry by morning. Most households that make the switch end up using both, with the dehumidifier taking the everyday loads and the dryer kept for the ones that cannot wait.

Set against a heated airer, the maths gets closer. A 300 watt heated airer running for four hours uses 1.2 kilowatt hours, around 31p. A dehumidifier in the same room for five hours uses about 0.76 kilowatt hours, around 20p. Running the two together dries a load faster than either alone, and still costs less than the dryer.

Six ways to cut the bill

• Set a humidity target of 50 to 55 per cent rather than using continuous mode, so the compressor switches itself off.
• Close the door of the room you are drying. A dehumidifier trying to dry a whole house never reaches target.
• Empty the tank before it fills, because a full tank stops the machine and you lose the hours you paid for.
• Clean the filter monthly. A blocked filter makes the fan work against resistance and cuts the water you get per unit.
• Use the laundry mode only when there is actual washing in the room, since it overrides the humidistat by design.
• Run it in the afternoon rather than the evening if you are on a time of use tariff, because peak rates between four and seven are where the expensive units live.

Is it worth having one at all

For a household with condensation on the windows every winter morning, yes, and the case is not really about the electricity. Mould remediation on a single bedroom wall costs more than five years of running a dehumidifier six hours a day, and damp plaster costs more than that again. The running cost question matters, but it is a smaller number than the one sitting behind it.

For a household with no visible damp and no drying problem, a dehumidifier is a machine that will sit in a cupboard. Buy the hygrometer first, spend a fortnight watching what the humidity in your rooms actually does, and then decide.