What does it cost to boil a kettle?
About 3p for a full one — and most of that is spent boiling water nobody drinks.
Typical model is rated 3,000W
Price cap is 26.11p
3p per boil, 2,190 boils a year, 241 kWh in total — about £5 a month.
Filling it for two mugs only
Energy scales with the amount of water, not the size of the kettle. Boiling 600ml instead of 1.7 litres uses roughly a third of the electricity.
£40 a year cheaper — £23 instead of £63.
A 3kW kettle is one of the most powerful things in the house, but it only runs for a couple of minutes, so each boil is cheap. The cost comes from repetition: a household boiling eight times a day does it nearly three thousand times a year.
Overfilling is the whole story. Energy goes into heating water, so filling to the top for one mug costs three times what it needs to. Doing that habitually is worth about the price of a weekly shop over a year.
Instant hot water taps are sold on this saving and rarely justify it. They keep a tank hot around the clock, which is a standing cost whether you use it or not — convenient, but not usually cheaper.
The short answer: About 1p for two mugs, 3p for a full kettle. Fill it to what you need and ignore the gadgets.
What actually helps
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This is the small stuff
Every appliance on this site put together is usually less than a third of a typical energy bill. Heating the house is the rest of it. If the numbers here bothered you, the number that actually matters is what your heating costs — and whether a heat pump would make it better or worse in your particular house.
Work out your heating costOther appliances
Energy figures checked 2026-08-26. Electricity priced at the Ofgem cap for 1 July – 30 September 2026. Your own machine and tariff will differ — put your figures in above.