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: 17 July 2026
Quick answer
The default scenario uses 4 250 ml cups, 4 boils a day and the 500 ml minimum fill.
The estimated kettle cost is £0.06 a day or £22.16 a year.
At 26.11 p/kWh for 1 July to 30 September 2026, this boils 1,000 ml more water than the cups need each day.
That extra water costs about £11.08 a year. The rate is editable and standing charge is excluded.
Calculator
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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. Kettle efficiency, water temperature and tariffs vary.
- Total water needed per day = cups per day x cup size
- Energy in kWh = water heated x temperature rise / efficiency
- Cost = kWh x electricity rate
Example calculation
A worked example helps the user compare the result with a familiar everyday scenario.
4 cups at 250 ml need 1,000 ml of water across the day. The default minimum-fill setting boils 500 ml each time.
At 26.11 p/kWh, that is £0.02 per boil, £0.06 per day and £22.16 per year. Boiling the extra water in this example accounts for £11.08 of the yearly estimate.
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 mainly on the amount of water you heat and your electricity rate. Enter your usual fill level and tariff to estimate the cost per boil.
- How many cups can I make from one kettle boil?
- Divide the water you boil by your cup size. For example, 500 ml covers two 250 ml cups, but allow for the amount you actually pour and use your own cup size for a closer estimate.
- Does filling the kettle too much cost more?
- Yes. Water you do not use still needs heating to boiling point. The calculator compares your cup count with the amount you boil to estimate the extra usage cost from overfilling.
- Can I use the electricity rate from my own bill?
- Yes. The default 26.11 p/kWh rate for 1 July to 30 September 2026 is editable, so you can replace it with the unit rate on your electricity bill.
- 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.
Sources and review
Source: Ofgem energy price cap unit rates and standing charges (1 July 2026 to 30 September 2026). Accessed 17 July 2026. Great Britain average Direct Debit fallback: 26.11p/kWh. Appliance estimates exclude the standing charge.
Assumptions: The default uses the Great Britain average Direct Debit electricity unit rate of 26.11 p/kWh for the current period, 1 July to 30 September 2026. You can edit the rate to match your bill. Water starts at 15°C, is heated to 100°C, and kettle efficiency is estimated at 85%.
Not included: Standing charge is excluded because boiling the kettle does not add a separate daily standing charge. Water use, gas costs and appliance repair or replacement costs are not included.
Reviewed by Hasan Kafadar. If you spot an issue, tell us how to correct it.
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.
Check the formula section and use your own bill where possible. For site details and policies, see:
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