How much does it cost to run an immersion heater in the UK?
Price updated 9 July 2026 · Q3 2026 (Jul–Sep)
A typical immersion heater (3,000 W) used 1.5 hours a day, every day costs about £35.74 a month (£428.86 a year) at 26.11p/kWh.
An immersion heater is essentially a giant kettle element in your hot water tank, rated around 3,000W. Heating a full tank from cold can take an hour or more and is one of the more expensive daily electricity uses in homes without gas hot water. The keys to cost are insulation and timing: a well-lagged tank holds heat for hours, and a timer that heats water only when you need it avoids paying to reheat a tank that then sits unused.
Work out your own cost
About £35.74 a month · £428.86 a year
Uses about 1,643 kWh a year. Prefilled with the Ofgem cap of 26.11p/kWh — edit any box for your own figures.
Cost by model power
The same immersion heater can vary a lot between models, so here is the range from a low-power to a high-power example.
| Model | Power | Per hour | Per day | Per month | Per year |
|---|---|---|---|---|---|
| Low-power model | 2,500 W | 65p | 98p | £29.78 | £357.38 |
| Typical model | 3,000 W | 78p | £1.17 | £35.74 | £428.86 |
| High-power model | 3,000 W | 78p | £1.17 | £35.74 | £428.86 |
What changes the cost
- Tank size and how cold the incoming water is
- Quality of the tank's insulation jacket
- Whether a timer heats it on demand or all day
- Thermostat setting
Common questions
How much does an immersion heater cost to run?
A 3kW element heating a tank for 1.5 hours uses about 4.5 kWh — well over £1 a day at the current cap, which is why timing and insulation matter so much.
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