Dehumidifier Running Cost: What It Really Costs Per Day, Week and Month
By Priya Shah, reviewed by James Whitfield · Updated
A dehumidifier is cheap to buy compared with the damp it prevents, but people still worry about the electricity bill. The good news is that the maths is simple: watts, hours and your unit rate. Here is how to work out the running cost of any model, what a typical compressor unit really draws, and the habits that keep the bill down.
The short answer
Most home compressor dehumidifiers draw somewhere between 250W and 500W while the compressor is running, which is roughly the same as a large desktop PC or a bright set of lights. Run for eight hours, that is about 2 to 4 kWh. A desiccant dehumidifier draws more, typically 300W to 600W or more, because it heats a rotor to release moisture. Your actual bill depends on your unit rate, how long the unit really runs, and whether the room is damp enough to keep the compressor working.
The formula: watts, hours and your unit rate
Every running-cost estimate comes from one formula: power in kilowatts × hours run × price per kWh. A 285W unit is 0.285 kW. Over 8 hours that is 0.285 × 8 = 2.28 kWh. Multiply by the unit rate printed on your latest electricity bill (in pence per kWh) to get the cost in pence. For example, at an illustrative 25p per kWh that 8-hour session costs about 57p; swap in your own tariff, because rates change and differ by supplier. Check the exact wattage on the label or in the manual rather than guessing, since the figure varies by model.
| Model | Type | Rated power | Energy over 8 hours |
|---|---|---|---|
| [De'Longhi Tasciugo AriaDry DEX212SF](/reviews/delonghi-tasciugo-ariadry-dex212sf/) | Compressor, 12L/day | 284W | about 2.3 kWh |
| [Bosch Dry 4000](/reviews/bosch-dry-4000/) | Compressor, 16L/day | 285W | about 2.3 kWh |
| [Russell Hobbs RHDH2002](/reviews/russell-hobbs-rhdh2002-20l/) | Compressor, 20L/day | 440W | about 3.5 kWh |
| [EcoAir DD1 Simple MK3](/reviews/ecoair-dd1-simple-mk3/) | Desiccant, 7.5L/day | 300W low / 580W high | about 2.4 kWh (low) to 4.6 kWh (high) |
Does a dehumidifier draw full power all the time?
Not usually. A compressor model cycles on and off as it chases your target humidity, and the humidistat stops the compressor when the room reaches the set level. In a room that is only mildly damp, the unit can spend a good part of the day idle apart from the fan, so the real daily energy is often well below the rated watts multiplied by 24 hours. A badly damp room, or one with ongoing sources such as wet laundry, keeps the compressor working for longer. This is why a first week of running is always the most expensive, and why costs settle down once the room is under control.
Compressor versus desiccant: which costs less to run?
In a typical heated UK home, a compressor dehumidifier removes more water per kWh than a desiccant model, so it is usually the cheaper option to run. A desiccant unit earns its place in cold rooms, garages and unheated outbuildings, where a compressor loses efficiency and can ice up. If you are weighing the two types, our guide on desiccant versus compressor dehumidifiers walks through the trade-offs, and our best dehumidifier for the UK pillar compares specific models by extraction rate and noise.
How to cut the running cost
Five habits make the biggest difference. Close the door and windows so you treat one room rather than the whole house. Choose the right capacity: an oversized unit finishes quickly and cycles off, while an undersized one runs flat out for hours. Use the humidistat at around 50 to 55% rather than the lowest setting, because chasing 35% wastes energy for no benefit. Clean the filter every couple of weeks, as a clogged filter makes the fan and compressor work harder. Run it in the warmest part of the day if you can, since compressor models extract more water in warmer air.
Laundry mode and the cost of drying clothes indoors
Many people buy a dehumidifier mainly to dry washing. A unit with a laundry mode runs the fan faster and holds humidity lower, which dries a rack of clothes in hours rather than days. It uses more power for that session than a gentle overnight run, but it usually costs less than a tumble dryer cycle for the same load, and it does not blow warm, humid air into the room. If drying washing is your main use, see our dedicated dehumidifier for drying clothes comparison and our guide on dehumidifier versus tumble dryer.
Is the running cost worth it?
Persistent damp and condensation cause peeling paint, musty smells and mould that cost far more to fix than the electricity used to prevent them. For health, the NHS asthma guidance lists damp and mould among common indoor triggers, and the GOV.UK guidance on damp and mould explains why tackling the cause matters. A dehumidifier treats the moisture in the air, but it does not fix a leak or a failed damp-proof course, so deal with the source first.
Ready to compare models? See our best dehumidifier uk comparison →
Frequently asked questions
How much does it cost to run a dehumidifier for 24 hours?+
Multiply the unit's wattage by 24, divide by 1,000 to get kWh, then multiply by your electricity rate. A 285W compressor model running non-stop would use about 6.8 kWh in a day, but in practice it cycles off once the room reaches its target humidity, so the real figure is usually lower.
Is it cheaper to run a dehumidifier or a tumble dryer?+
For the same load of washing, a dehumidifier with a laundry mode normally uses less electricity than a vented or condenser tumble dryer, though it takes longer. It also avoids the wear on clothes that comes with high heat.
Do desiccant dehumidifiers cost more to run?+
Usually yes in a warm room, because they heat a rotor to release moisture and draw more power per litre removed. They cost less to run than a struggling compressor unit in a very cold space, which is where they make sense.
Should I leave a dehumidifier on all day?+
Only while the room is damp. Use the humidistat at around 50 to 55% so the unit switches itself off at target, and use continuous drainage if you do not want to empty the tank repeatedly.
Does a bigger dehumidifier cost more to run?+
A higher-capacity model generally draws more watts, but it also reaches the target humidity faster and then cycles off, so the daily energy can be similar to a smaller unit that runs for much longer.