How much does a dehumidifier cost to run?
A typical compressor dehumidifier rated around 200W costs about 5.3p an hour at the Ofgem cap rate of 26.32p/kWh. A desiccant model around 600W costs about 16p an hour. Eight hours a day for a month comes to roughly £12.63 for the compressor model and £37.90 for the desiccant one, if both ran non-stop. A humidistat usually cuts that down.
Prices last checked: 26 September 2026 · Source: Ofgem energy price cap, 1 October to 31 December 2026 · Great Britain average, standard variable tariff, paid by Direct Debit
Dehumidifier cost per hour, day and month
| Type | Energy per hour | Cost per hour | Per day (8 h) | Per 30 days |
|---|---|---|---|---|
| Small compressor (150W) | 0.15 kWh | 3.9p | 32p | £9.48 |
| Mid-size compressor (250W) | 0.25 kWh | 6.6p | 53p | £15.79 |
| Large compressor (400W) | 0.4 kWh | 11p | 84p | £25.27 |
| Desiccant (600W) | 0.6 kWh | 16p | £1.26 | £37.90 |
| Desiccant on high (700W) | 0.7 kWh | 18p | £1.47 | £44.22 |
Compressor or desiccant: which is cheaper for you?
Compressor dehumidifiers work like a small fridge. Air passes over a cold coil and water condenses out. They use less power, but they get much less effective as the room gets colder, because the coil can ice up and the unit spends time defrosting.
Desiccant dehumidifiers pull water into an absorbent material, then heat it to drive the water off. They use more power, but they keep working in cold rooms and give off noticeable warmth.
Compressor tends to win
In a heated home at normal room temperature, and for all-year damp control. The lower wattage adds up over hundreds of hours.
Desiccant tends to win
In an unheated garage, conservatory or spare room in winter, where a compressor model would struggle. The waste heat is also useful when you are drying laundry in a cold room.
Drying clothes with a dehumidifier
Many people buy a dehumidifier to dry washing indoors without the condensation. Put the airer and the dehumidifier in a small room with the door closed and the laundry setting on. A load often dries in a few hours. At 250W, four hours is 1 kWh, about 26p. That compares well with a conventional tumble dryer, but it is slower. It also works better in a small, closed space than a large open-plan room.
Compare with the tumble dryer and heated airer pages before you decide what to buy.
How to keep the cost down
- Use the humidistat. Setting a target humidity (many people use somewhere around 50–60%) lets the unit stop once the room is dry instead of running all day.
- Close doors and windows while it runs. Otherwise it is trying to dry the whole house, or the weather.
- Fix the source. Extractor fans in bathrooms and kitchens, lids on pans and not drying clothes on radiators all reduce how much moisture you need to remove.
- Clean the filter. A clogged filter makes the unit run longer for the same result.
Common mistakes
- Guessing the wattage from the litres-per-day number.
- Running a compressor model in a very cold room and wondering why the tank barely fills.
- Assuming 24 hours at full power. A humidistat can cut the running time a lot once the room is dry.
Limits of this estimate
The unit rate is the Ofgem cap average for Great Britain on Direct Debit. Real power draw varies with fan speed, room temperature and defrost cycles. For an exact figure, run the unit on a plug-in energy monitor for a day.
Frequently asked questions
Is it expensive to run a dehumidifier all day?
A 250W compressor unit running for 24 hours uses 6 kWh, about £1.58. With a humidistat it will normally run for much less of the day.
Is a dehumidifier cheaper than a tumble dryer for drying clothes?
Usually yes per load, if you compare a compressor dehumidifier with a conventional vented or condenser dryer. A heat-pump dryer narrows the gap and is much faster.
Does a dehumidifier help heat the room?
A little. Both types give off some warmth, and desiccant models noticeably so. Drier air can also feel slightly warmer. It is not a substitute for heating.