UK running cost calculator
Kettle Cost Calculator UK
Estimate how much it costs to boil a kettle in the UK, then see how much extra water could be adding to the bill.
Last reviewed: 25 April 2026
Calculator inputs
Choose how many cups you make, how big they are, and how full the kettle usually gets.
Result Card
Estimated kettle cost
Based on boiling 500 ml 4 times a day at 24.67 p/kWh. Around 1 litres a day is more than your cups need.
500 ml boiled each time
4 boils per day
Daily cost x average month
Daily cost x 365
£0.03 per day from 1 litres of extra water
Boiling only what you need could reduce wasted energy.
On your current settings, around 1 litres a day may be extra water, which could add about £10.47 over a year.
How this estimate works
See the exact steps behind the estimate so the result stays easy to sense-check.
This calculator estimates the energy needed to heat water from 15°C to boiling point, then applies the current default UK electricity unit rate. It is an estimate because kettle efficiency, water temperature and tariff can vary.
- Total water needed per day = cups per day x cup size
- Energy in kWh = litres boiled x 4.186 x 85 / 3600 / 0.85
- Cost = kWh x electricity rate
Electricity rate source: Ofgem energy price cap unit rates.
Example calculation
A worked example helps the user compare the result with a familiar everyday scenario.
4 cups at 250 ml needs 1 litres of water across the day.
If you boil 500 ml each time, that works out to about £0.06 per day and £10.47 of extra cost per year from overfilling.
Tips to reduce cost
Small household changes can often reduce running costs without overcomplicating the decision.
- Boil only the water you need for the cups you are making right now.
- If you often make one drink at a time, the 500 ml minimum can still be more than you need.
- Limescale can make appliances work less efficiently, so descale the kettle regularly.
- If several drinks are needed together, one fuller boil may be better than repeated smaller ones.
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Kettle cost questions
Short answers to common kettle cost questions.
How much does it cost to boil a kettle once?
It depends on how much water you boil and your tariff. A smaller fill usually costs less than boiling half or a full kettle.
Why can overfilling waste money?
Extra water still needs heating to boiling point. If you regularly boil more than your cups need, that extra energy adds up over time.
Does this include standing charge?
No. Standing charge is not included because this page estimates the usage cost of the kettle itself, not the full electricity bill.
Estimate notice
This is an estimate. Your actual cost may vary depending on your tariff, kettle efficiency, starting water temperature and how full you boil the kettle.