Electricity Cost Calculator UK
Example rate: 26.32p/kWh — the Ofgem price-cap average for Direct Debit customers, 1 October to 31 December 2026. Change it to the rate on your bill.
Model: cost = energy used (kWh) × unit rate. A month is 365 ÷ 12 = 30.44 days. This covers the unit-rate part of your bill only — your standing charge (54.83p a day at the October 2026 cap) is on top, and is charged even if you use nothing.
How to work out electricity cost in three steps
Every electricity bill in the UK is built from the same two numbers: how many kilowatt-hours (kWh) you used, and what your supplier charges per kWh. A kilowatt-hour is simply 1,000 watts used for one hour. So a 1,000-watt heater running for one hour uses exactly 1 kWh. A 100-watt light bulb needs ten hours to use the same 1 kWh. Once you know the kWh, multiply by your unit rate and you have the cost.
Step one: find the watts. It is printed on the appliance, on its plug, or in the manual — look for a number followed by W. If it only gives amps, multiply amps by 230 (UK mains voltage) to get watts. Step two: work out the kWh. Divide watts by 1,000 to get kilowatts, then multiply by the hours used. A 2,500-watt tumble dryer running for one hour uses 2.5 kWh. Step three: multiply by your unit rate. At 26.32p per kWh, that hour of drying costs 66p. Do the same maths for a day, a week or a year and the running cost of anything in your home stops being a mystery.
What the Ofgem price cap actually is
The price cap is set by Ofgem, the energy regulator, and it changes every three months. For 1 October to 31 December 2026 the cap works out at £1,723 a year for a typical household paying by Direct Debit — but that headline number is the part most people misunderstand. The cap does not cap your bill. It caps the unit rate and the standing charge your supplier can charge you on a standard variable (default) tariff. Use more electricity and you pay more, however high or low the cap is.
The capped rates for October to December 2026 are 26.32p per kWh for electricity, with a standing charge of 54.83p a day, and 7.97p per kWh for gas, with a standing charge of 29.68p a day. Those are Great Britain averages for Direct Debit customers; your exact rates depend on where you live, how you pay, and your meter type. The next cap, for 1 January to 31 March 2027, was due to be announced by 25 November 2026, so if you are reading this after that date, check Ofgem’s site for the new figure and type it into the calculator. One more thing that changed in 2026: the government removed VAT from domestic electricity from 1 October 2026, and the Autumn Budget on 28 October 2026 extended that zero rate to 30 June 2027, while gas still carries 5% VAT. That is already reflected in the 26.32p figure.
Worked examples at the October 2026 cap rate (26.32p/kWh)
| Appliance | Watts | Use | Cost |
|---|---|---|---|
| LED light bulb | 10 W | 5 hours a day | £0.01 a day, £4.80 a year |
| TV (LED, 55 inch) | 100 W | 4 hours a day | £0.11 a day, £38.43 a year |
| Laptop | 60 W | 8 hours a day | £0.13 a day, £46.11 a year |
| Washing machine | 500 W | 1 hour a day | £0.13 a day, £48.03 a year |
| Electric oven | 2,000 W | 1 hour a day | £0.53 a day, £192.14 a year |
| Tumble dryer | 2,500 W | 1 hour, 3 times a week | £0.66 a use, £102.65 a year |
| Electric heater | 2,000 W | 4 hours a day | £2.11 a day, £768.54 a year |
| Kettle | 3,000 W | 3 minutes, twice a day | £0.08 a day, £28.82 a year |
The heater row is the one that surprises people. A single 2 kW electric heater left on for four hours every evening costs more than £2 a day — over £60 a month in winter. That is why heating is almost always the biggest part of an electricity bill, and why a draughty room heated with a plug-in heater is one of the most expensive ways to stay warm. By contrast, LED lighting is almost free: a 10-watt bulb costs less than 2p for five hours.
Why your bill is higher than the calculator says
If you add up every appliance and still fall short of your bill, the gap is usually one of four things. First, the standing charge: 54.83p a day is £200.13 a year before you switch anything on. Second, appliances on standby. A TV, a games console, a set-top box and a router left on standby can draw 5 to 15 watts each, all day, every day — at 26.32p per kWh, 10 watts running 24 hours a day costs £23.07 a year. Third, appliances whose wattage is not what you think. A washing machine rated at 500 watts may draw 2,000 watts while it heats water, so a hot wash costs far more than a cold one. Fourth, your actual unit rate: if you are on a fixed tariff, a prepayment meter, or an Economy 7 tariff with different day and night rates, the cap average does not apply to you. The rate on your bill is the one that matters, and it is printed on every statement.
Five ways to cut the number the calculator gives you
- Heat water less. Wash clothes at 30°C instead of 60°C and only boil as much water as you need in the kettle. Heating water is the most expensive thing most appliances do.
- Use the dryer less. At 66p an hour, three loads a week cost £102.65 a year. A drying rack costs nothing.
- Kill standby. Switch off at the wall, or use a switched extension lead for the TV corner. A few pounds a year per device adds up across a house.
- Swap the bulbs. An old 60-watt bulb costs six times as much to run as a 10-watt LED giving the same light.
- Check your tariff. The cap rate is the most you can pay on a standard variable tariff, not the cheapest rate available. A fixed deal may be lower — but read the exit fees before you switch.
Related: Energy Bill Calculator · Appliance Running Cost Calculator · Compound Interest Calculator
Sources: Ofgem, “Energy price cap” and price cap unit rates and standing charges, 1 October to 31 December 2026 (electricity 26.32p/kWh, standing charge 54.83p/day; typical household £1,723). Checked 13 November 2026.