Dehumidifier Running Cost Calculator
Work out what a compressor or desiccant dehumidifier costs to run per hour, day and year from its watts and how long it runs.
Quick answer
A typical 10 to 12 litre compressor dehumidifier draws about 160 W, so 8 hours a day at an 80% duty cycle uses 1.02 kWh and costs about 27p a day at the Ofgem cap rate of 26.32p/kWh (October to December 2026). That is 3.4p per hour switched on and about £48.51 over a 180-day damp season. A 650 W desiccant model on the same settings costs about £1.09 a day.
How to use the dehumidifier running cost calculator
- Choose the dehumidifier type. Pick compressor or desiccant. Each loads a typical power draw that you can replace with the wattage from your own unit’s label or manual.
- Enter the power draw. Use the rated watts, or the reading from a plug-in energy monitor for the most accurate result. Desiccant units draw more on high and laundry modes than on low.
- Enter the hours and duty cycle. Type how many hours a day the unit is switched on, then the share of that time it runs at full power. A humidistat switches the compressor or heater off once the room reaches its target.
- Enter the days per year and your unit rate. 180 days covers October to March. The rate defaults to the Ofgem price cap average of 26.32p/kWh.
- Read the running cost per day. The large number is the daily cost. The cards show the cost per hour switched on, per month, per year and the kWh used each year.
Dehumidifier running cost formula
The calculator multiplies power by the time spent at full draw, then prices the energy.
Where:
- Eday is the electricity used per day in kWh.
- P is the power draw in watts while the dehumidifier is working.
- h is the hours switched on per day.
- D is the duty cycle as a decimal: 0.8 means it runs at full power 80% of the time.
- R is the unit rate in £ per kWh, such as £0.2632.
- days is the number of days you use it in a year. The monthly card assumes daily use for 30.42 days.
Worked examples
Example 1: 12 litre compressor unit in a bedroom
The default. A 160 W compressor model runs 8 hours a day and works 80% of that time.
That is 1.02 kWh a day. Over 180 days the dehumidifier uses 184 kWh and costs £48.51.
Example 2: desiccant unit drying laundry
A desiccant model on laundry mode draws about 650 W with no humidistat cut-out, so the duty cycle is 100%. Drying one rack for 6 hours, once a week (52 days a year):
The year’s laundry drying uses 203 kWh and costs £53.38. A full 8 kg load in a condenser tumble dryer costs about £1.22, so the two are close for a full load.
Example 3: 20 litre unit running all year
A larger 250 W compressor model in a damp basement stays on 24 hours a day, but the humidistat keeps it working only half the time.
Over 365 days it uses 1,095 kWh and costs £288.20 a year.
Dehumidifier cost per hour and per day by wattage
Costs at full power (100% duty cycle) and 26.32p/kWh. The 157 W row is the published draw of the Meaco 12L Low Energy at 20°C and 60% humidity, and 330 W and 650 W are the low and high settings of a common 8 litre desiccant model.
| Power draw | Typical unit | Cost per hour | Cost per 24 hours |
|---|---|---|---|
| 120 W | Small compressor, eco mode | 3.16p | 76p |
| 157 W | 12 L low-energy compressor | 4.13p | 99p |
| 200 W | 12 to 20 L compressor | 5.26p | £1.26 |
| 250 W | 20 L compressor | 6.58p | £1.58 |
| 330 W | Desiccant, low setting | 8.69p | £2.09 |
| 400 W | Large compressor | 10.53p | £2.53 |
| 650 W | Desiccant, high or laundry | 17.11p | £4.11 |
What affects the result
Compressor or desiccant
A compressor dehumidifier works like a small fridge, condensing water on a cold coil. It extracts the most water per kWh in rooms above about 15°C. A desiccant model absorbs moisture in a rotating wheel, then heats the wheel to release it, which takes more power. The upside is that nearly all that energy ends up as heat in the room, and desiccant units keep working in cold garages, boats and lofts.
Duty cycle and humidistat setting
Most units stop working hard once the room reaches the set humidity, often 50 to 60%. In a sealed room the duty cycle can fall below 50% after the first day. Laundry mode and continuous mode ignore the humidistat, so use 100% for those.
Room temperature and humidity
Power draw rises in warm, wet air. The Meaco 12L Low Energy data shows 138 W at 10°C and 60% humidity, rising to 200 W at 30°C and 80%. Extraction rises much faster than power, so a damp room is dried more efficiently.
Your electricity rate
The default 26.32p/kWh is the average Direct Debit unit rate under the Ofgem price cap for 1 October to 31 December 2026. Fixed and time-of-use tariffs differ, and running the unit on cheap overnight hours lowers the cost. If a desiccant unit is also warming the room, compare it with the electric heater running cost calculator.
Frequently asked questions
How much does it cost to run a dehumidifier for 24 hours?
At 26.32p/kWh a 160 W compressor unit costs about £1.01 if it ran flat out for 24 hours, but with a humidistat it typically runs 50 to 80% of the time, so 51p to 81p. A 650 W desiccant unit on high costs about £4.11 for a full 24 hours.
Is it cheaper to run a dehumidifier or a tumble dryer?
For drying laundry, a compressor dehumidifier is usually cheapest. A 200 W unit running 6 hours costs about 32p, while a condenser tumble dryer load costs about £1.22. A 650 W desiccant unit costs about £1.03 for 6 hours, close to the dryer, but it also warms the room.
Do dehumidifiers use a lot of electricity?
Not compared with heating. A typical home compressor model draws 150 to 250 W, less than a quarter of a small fan heater. Running 8 hours a day for the damp half of the year at an 80% duty cycle uses about 170 to 290 kWh, or roughly £45 to £76 at the October 2026 cap rate.
Should I leave my dehumidifier on all the time?
Only if the space is persistently damp, such as a basement or a room with a known moisture problem. Set the humidistat to around 50 to 55% so the unit switches itself off once the air is dry enough. Leaving it on with no humidistat wastes energy and can over-dry the air.
Does a dehumidifier help heat a room?
Yes, a little. A compressor unit releases the energy it uses plus the latent heat from condensing water, so the room warms slightly. A desiccant unit gives off almost all its electricity as heat, making it act like a small heater, which suits cold rooms but adds cost in summer.