How Much Does It Cost to Run an Evaporative (Swamp) Cooler in the UK? (2026)
An evaporative cooler is only a fan and a small pump, so it uses a quarter or less of the electricity of an air conditioner of similar cooling capacity. It only works well in dry climates.
A typical evaporative (swamp) cooler (300 W) costs £0.079 per hour, or about £18.95 per month at 8 hours a day in the UK. Average running cost
| Wattage | Per hour | Per day | Per month | Per year |
|---|---|---|---|---|
| Low 100 W | £0.026 | £0.21 | £6.32 | £25.27 |
| Typical 300 W | £0.079 | £0.63 | £18.95 | £75.80 |
| High 800 W | £0.21 | £1.68 | £50.53 | £202.14 |
Formula: watts ÷ 1000 × hours × price per kWh. Typical use is 8 h/day for about 120 days a year (the cooling season) ≈ 288 kWh per year.
One hour of an evaporative (swamp) cooler (0.30 kWh) is the same electricity as
- 2.1minutes of electric shower
- 3.0hours of TV
- 20phone charges
- 33hours of an LED bulb
In the UK, with electricity at 26.3p per kWh (source: Ofgem price cap 1 Oct–31 Dec 2026, 2026-10), a typical evaporative (swamp) cooler costs £0.079 per hour and about £75.80 per year at 8 hours a day. Each £1.00 of electricity buys roughly 12.7 hours of use.
How to lower the cost of running an evaporative (swamp) cooler
- Open a window on the far side of the room. Swamp coolers need airflow out to work.
- Replace pads each season. Clogged pads cut cooling and make the fan work harder.
- Run the pump a few minutes before the fan so pads are wet from the start.
Frequently asked questions
Is a swamp cooler cheaper to run than AC?
Yes, typically 3 to 5 times cheaper per hour, but it cannot cool a humid room.
How much water does an evaporative cooler use?
Around 10 to 25 litres per hour for a whole-house unit, less for portable ones.
Can I run a swamp cooler all day?
Yes. At 300 watts, 24 hours uses 7.2 kWh, about the same as an AC running two to three hours.
Cost by region
US states
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- District of Columbia
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
Canadian provinces
Related appliances
- Electric Blanket100 W typical
- Heat Pump (Ducted or Mini-Split)2,000 W typical
- Baseboard Heater1,500 W typical
- Portable Fan (Box or Pedestal)50 W typical
Use the generic electricity cost calculator · Which uses more? Take the quiz