Running costs · price cap 1 July to 30 September 2026
How much does an immersion heater cost to run?
An immersion heater rated at 3,000 W uses 3 kWh an hour, which costs about 78p an hour at the current price cap of 26.11p per kWh. Used for 1 hour a day, that is 78p a day, £23.50 over a 30-day month or £285.90 a year.
Prices checked against Ofgem on .
Per hour
78p
3,000 W
Per day
78p
for 1 hour
per year
£285.90
at 1 hour a day
Unit rate
26.11p
per kWh, price cap
Immersion heater running cost by time used
At 3,000 W and 26.11p per kWh. The week and year columns assume the same use every day.
| Time on | Per day | Per week | Per year |
|---|---|---|---|
| 10 minutes | 13p | 91p | £47.65 |
| 30 minutes | 39p | £2.74 | £142.95 |
| 1 hour | 78p | £5.48 | £285.90 |
| 2 hours | £1.57 | £10.97 | £571.81 |
| 4 hours | £3.13 | £21.93 | £1,143.62 |
| 8 hours | £6.27 | £43.86 | £2,287.24 |
Immersion heater running cost by electricity price
Monthly and yearly cost at the same usage. Fixed deals vary, so check the unit rate on your bill.
| Tariff | Unit rate | Per month | Per year |
|---|---|---|---|
| 1 July to 30 September 2026 price cap | 26.11p | £23.83 | £285.90 |
| 1 October to 31 December 2026 price cap | 26.32p | £24.02 | £288.20 |
| A 20p per kWh fixed deal | 20p | £18.25 | £219.00 |
| A 24p per kWh fixed deal | 24p | £21.90 | £262.80 |
| A 30p per kWh fixed deal | 30p | £27.38 | £328.50 |
How the cost is worked out
Watts ÷ 1,000 × hours × unit rate. For this immersion heater: 3,000 ÷ 1,000 × 1 hour × 26.11p = 78p an hour. Check the rating plate on your own immersion heater, as models vary.
From 1 October
The price cap changes to 26.32p per kWh from 1 October to 31 December 2026. At the usage above, an immersion heater would cost £288.20 a year, £2.30 more than now.
Guides and definitions
- Energy price cap explained: rates from 1 October 2026 and your bill (Guide)
- Is Economy 7 worth it? Hours, price cap and the night-use break-even (Guide)
- Standing charge vs unit rate: which energy tariff is cheaper for you? (Guide)
- Economy 7 (Economy 7 is an electricity tariff with seven cheaper off-peak hours, usually overnight, and a dearer daytime rate; Ofgem assumes 42% of use falls off-peak.)
- Typical domestic consumption values (TDCVs) (Typical domestic consumption values are Ofgem's yearly usage figures for a typical home, 2,500 kWh electricity and 9,500 kWh gas from 1 July 2026.)
- Energy price cap (The energy price cap is Ofgem’s limit on unit rates and standing charges for default tariffs; typical bill £1,723 from 1 October 2026.)
- Standing charge (A standing charge is the fixed daily amount on an energy bill, paid whatever you use; the capped average is 54.83p a day for electricity.)
Other appliances
- Air fryer (running costs)
- Kettle (running costs)
- Fridge freezer (running costs)
- TV (running costs)
- Electric shower (running costs)
- Electric heater (running costs)
- Oil-filled radiator (running costs)
- Dehumidifier (running costs)
- Microwave (running costs)
- Electric hob (running costs)
Appliance running cost calculator · Use your own wattage and unit rate
Common questions
How much does an immersion heater cost to run per hour?
About 78p an hour for a 3,000 W model at 26.11p per kWh.
How much does an immersion heater cost to run a day?
About 78p if you use it for 1 hour. Double the time and the cost doubles.
How many watts does an immersion heater use?
The Centre for Sustainable Energy gives an average rating of 3,000 W. Yours will be on the label or rating plate.
Sources and assumptions
- Prices use the Ofgem price cap for 1 July to 30 September 2026: 26.11p per kWh, the average for Direct Debit customers in England, Scotland and Wales. Northern Ireland is not covered by the cap.
- Power ratings are the average figures published by the Centre for Sustainable Energy. Check the label on your own appliance for its wattage.
- The daily standing charge (57.19p a day) is paid whatever you use, so it is not included.
- Ofgem: energy price cap unit rates and standing charges
- Centre for Sustainable Energy: how much electricity am I using? (reviewed July 2026)
These are estimates. Your bill depends on your tariff, your region and how you use the appliance.