Cost to run an immersion heater
An immersion heater drawing 3,000 W costs 79p for each hour of running at 26.32p/kWh. Used 2 hours a day, every day, that comes to £48.03 a month.
An hour of running costs
79p an hour
That is 3.00 kWh. Used as set, it comes to £48.03 a month and £576.41 a year.
On the label or in the manual.
Standby, thermostats and off-peak use
A thermostat switches it on and off to hold a temperature. 100% if it runs flat out.
Drawn while plugged in and not running.
| Period | Cost | Energy | CO2e |
|---|---|---|---|
| An hour of running | 79p | 3.00 kWh | 652 g |
| A day, on average | £1.58 | 6.00 kWh | 1.3 kg |
| A month | £48.03 | 183 kWh | 39.7 kg |
| A year | £576.41 | 2,190 kWh | 476 kg |
How we calculated this
Energy is power multiplied by time: 3,000 W running for an hour uses 3.00 kWh.
The starting use for an immersion heater, 2 hours a day, every day, is where the calculator starts, not a measurement of your home: change it to how you use yours. A day is the average across the week, and a month is a twelfth of a 365-day year.
Electricity costs 26.32p/kWh. That is the published figure for the United Kingdom, 1 Oct – 31 Dec 2026, from Ofgem. Average for England, Scotland and Wales, paying by Direct Debit. No VAT on electricity from 1 October 2026 to 31 March 2027.
Standing charges are left out: you pay them whether or not the appliance runs.
Emissions use 0.217 kg CO2e per kWh, the lifecycle intensity of electricity generated in the United Kingdom in 2025, from Ember, via Our World in Data. Lifecycle means building the power stations and supplying their fuel are counted too. It is the grid’s average, not the particular power station an extra appliance brings on.
What drives the cost
An immersion heater is an electric element inside the hot water cylinder, and it draws 3,000 W while it heats, until the thermostat says the water is hot enough. What it costs depends on how often it has to heat, which is set by how much hot water you use and how well the cylinder holds its heat.
Also called: immersion, hot water cylinder heater, hot water tank.
What it costs in the UK, Europe and the US
For an immersion heater used as typical (2 hours a day, every day), at each country’s published average electricity price.
| Country | Electricity price | An hour |
|---|---|---|
| United Kingdom | 26.32p/kWh | 79p |
| United States (average) | 18.19¢/kWh | 54.6¢ |
| Ireland | €0.4042/kWh | €1.21 |
| Germany | 0,3869 €/kWh | 1,16 € |
| France | 0,2561 €/kWh | 0,77 € |
| Spain | 0,2669 €/kWh | 0,80 € |
| Italy | 0,2966 €/kWh | 0,89 € |
| Netherlands | € 0,2558/kWh | € 0,77 |
Compared with similar appliances
Every electric heater here turns each kWh it uses into a kWh of heat, so at 26.32p/kWh a kWh of heat costs the same whichever you run. A more powerful heater costs more an hour because it gives out more heat, not because it wastes any. Only a heat pump gets more heat from a kWh, because it moves heat in from outside rather than making it.
| Appliance | Typical power | An hour | A year, typical use |
|---|---|---|---|
| Immersion heater | 3,000 W | 79p | £576.41 |
| Electric water heater | 5,000 W | £1.32 | £1,441.02 |
| Electric shower | 9,000 W | £2.37 | £230.56 |
How to spend less on it
- Fit a timer so it heats only when you need hot water, or in off-peak hours if your tariff has them.
- Turn the thermostat down to the lowest setting that gives you hot enough water: a hotter cylinder loses more heat.
- Insulate the cylinder and the pipes near it: less heat lost means fewer hours of heating.
Questions
How much does an immersion heater cost to run per hour?
At 26.32p/kWh, an immersion heater drawing 3,000 W costs 79p for every hour of running at full power.
How much does an immersion heater cost to run a year?
Used 2 hours a day, every day, it costs about £576.41 a year at 26.32p/kWh, or £48.03 a month.
Is it cheaper to leave the immersion heater on all the time?
Usually not. A well-insulated cylinder loses little heat, but leaving the element on keeps replacing what does leak. Heating only when you need hot water, or in off-peak hours if your tariff has them, costs less.
Sources
- How much electricity am I using?, Centre for Sustainable Energy, July 2026. “Immersion heater (3000 W)”
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