Home / Cost to run / Hot water
How much does it cost to run an immersion heater?
An immersion heater costs about 79p an hour to run.
Work out your cost
Find the wattage on the label or rating plate, usually on the back or underneath.
Low, typical and high running costs
Using 1.5 hours a day.
| Rating | Unit cost | Per week | Per year | |
|---|---|---|---|---|
| Low | 3,000W | 79p / hour | £8.29 | £432.31 |
| Typical | 3,000W | 79p / hour | £8.29 | £432.31 |
| High | 3,000W | 79p / hour | £8.29 | £432.31 |
How it compares
| Appliance | Typical use | Per day | Per month |
|---|---|---|---|
| Storage heater | 7 hours a day | £2.14 | £65.15 |
| Hot tub | switched on all day | £2.11 | £64.05 |
| Oil-filled radiator | 4 hours a day | £1.47 | £44.83 |
| Fan heater | 3 hours a day | £1.26 | £38.43 |
| Immersion heater | 1.5 hours a day | £1.18 | £36.03 |
| Electric shower | 10 minutes a day | 40p | £12.25 |
How we work it out
Cost per hour = watts ÷ 1,000 × share of time at full power × price per kWh. For a 3,000W immersion heater at 100%: 3,000 ÷ 1,000 × 1 × 26.32p = 79p.
The low, typical and high figures are for models sold in the UK, taken from the sources below. Your own appliance may differ, so check its rating plate or energy label for the most accurate figure.
Sources
- Ofgem: changes to the energy price cap, 1 October to 31 December 2026
- National Energy Action: Electricity leaflet (June 2025)
- Centre for Sustainable Energy: What uses watt? (2022)
Questions
How much electricity does an immersion heater use?
Most use between 3,000W and 3,000W. A 3,000W model running at full power uses 3 kWh an hour.
How much does an immersion heater cost to run per day?
Used for 1.5 hours a day it costs about £1.18, based on the Ofgem price cap rate of 26.32p per kWh.
Where does the electricity price come from?
We use the Ofgem price cap average for Great Britain, paying by Direct Debit: 26.32p per kWh for 1 Oct 2026 to 31 Dec 2026. Electricity rate includes 0% VAT, which applies from 1 October 2026 to 31 March 2027. Storage heater and EV pages use an off-peak rate instead. Your own tariff may be higher or lower, so check your bill and enter your rate in the calculator.