Cost to run an electric water heater
An electric water heater drawing 5,000 W costs £1.32 for each hour of running at 26.32p/kWh. Used 3 hours a day, every day, that comes to £120.09 a month.
An hour of running costs
£1.32 an hour
That is 5.00 kWh. Used as set, it comes to £120.09 a month and £1,441.02 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 | £1.32 | 5.00 kWh | 1.1 kg |
| A day, on average | £3.95 | 15.0 kWh | 3.3 kg |
| A month | £120.09 | 456 kWh | 99.2 kg |
| A year | £1,441.02 | 5,475 kWh | 1.2 t |
How we calculated this
Energy is power multiplied by time: 5,000 W running for an hour uses 5.00 kWh.
No source calls one figure typical, so the typical figure is the middle of Virginia Tech’s nameplate range for the tank water heater in its table, and the low and high figures are its ends.
The starting use for an electric water heater, 3 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 electric water heater draws 5,000 W while its elements heat the tank, and switches off once the water is at temperature. It is one of the biggest electric loads in a home, so the hours it runs each day matter more than almost anything else on the bill.
Also called: hot water heater, water tank heater, geyser.
What it costs in the UK, Europe and the US
For an electric water heater used as typical (3 hours a day, every day), at each country’s published average electricity price.
| Country | Electricity price | An hour |
|---|---|---|
| United Kingdom | 26.32p/kWh | £1.32 |
| United States (average) | 18.19¢/kWh | 91¢ |
| Ireland | €0.4042/kWh | €2.02 |
| Germany | 0,3869 €/kWh | 1,93 € |
| France | 0,2561 €/kWh | 1,28 € |
| Spain | 0,2669 €/kWh | 1,33 € |
| Italy | 0,2966 €/kWh | 1,48 € |
| Netherlands | € 0,2558/kWh | € 1,28 |
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 |
|---|---|---|---|
| Electric water heater | 5,000 W | £1.32 | £1,441.02 |
| Immersion heater | 3,000 W | 79p | £576.41 |
| Electric shower | 9,000 W | £2.37 | £230.56 |
How to spend less on it
- Turn the thermostat down to the lowest setting that gives you hot enough water: a hotter tank loses more heat and runs longer.
- Insulate the tank and the first stretch of pipe, and fix dripping hot taps: every litre that runs away has to be heated again.
- Use a timer, or a smart controller, to heat in off-peak hours if your tariff has them.
Questions
How much does an electric water heater cost to run per hour?
At 26.32p/kWh, an electric water heater drawing 5,000 W costs £1.32 for every hour of running at full power.
How much does an electric water heater cost to run a year?
Used 3 hours a day, every day, it costs about £1,441.02 a year at 26.32p/kWh, or £120.09 a month.
How many watts does an electric water heater use?
Most draw between 4,500 W and 5,500 W while running, and 5,000 W is typical. The rating is on the label or in the manual.
How much does an electric water heater cost to run?
At 5,000 W it costs £1.32 for every hour its elements are on. Used 3 hours a day, every day, that comes to about £1,441.02 a year at 26.32p/kWh, though how long the elements are on depends on how much hot water you use.
Sources
- ENERGY SERIES: Estimating Appliance and Home Electronic Energy Use, Virginia Cooperative Extension, Virginia Tech, 26 February 2020. “Water heater (40 gallon) = 4500–5500”
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