Estimated monthly electricity costCalculating...

How the energy cost estimate works

The calculator converts watts into kilowatts, multiplies by hours used, then applies your electricity unit rate in pence per kWh. For example, a 1,000 W appliance uses 1 kWh for every hour it runs.

Estimate only: real energy use can vary with thermostat cycling, eco modes, standby power, appliance age, load size, room temperature, tariff changes and whether the appliance runs at full power the whole time.

Watts and kWh

Watts describe power at a moment. kWh describes energy used over time and is what electricity tariffs usually charge for.

Standing charge

Standing charge is optional here. Include it only if you want to allocate the daily fixed cost to this estimate.

Source note

Default unit-rate wording checked against Ofgem price-cap unit-rate guidance on 19 July 2026. Use your own bill or tariff for a better estimate.

Appliance examples to test

Try comparing a heater for two hours a day, a tumble dryer used a few times a week, a TV used every evening, or a laptop used during a workday. The monthly total can make occasional high-power appliances easier to compare with low-power devices used for many hours.

For whole-home planning, run several appliance scenarios and add the monthly costs together. Check your actual bill or smart meter for the source of truth, because heating, hot water, refrigeration and standby usage can dominate household energy use.

Common energy cost mistakes

Do not assume the label wattage is always the real running power. A heater may cycle on and off, a fridge compressor does not run continuously, a washing machine uses different power during heating and spinning, and a laptop charger may draw less once the battery is full.

Standing charges are fixed daily costs for the electricity supply, not the cost of a specific appliance. Include them only when you want a whole-bill style estimate. For comparing appliances, the unit-rate-only energy cost is usually the cleaner comparison.