1,000 watts for one hour equals 1 kWh only when power stays at 1,000 W throughout.
The result is not a supplier bill or quote. Unit rates, standing charges, region, payment method, meter type, tariff, VAT, discounts, debt and support schemes can differ. Use values from the same tariff period and bill for a personal check.
Calculate a 1 kW load
Change watts for a different appliance.
The calculation runs in your browser. Values are not sent to the website.
How the calculation works
Cost = 1 kW × hours × £/kWh.
Unit-rate energy and daily standing charges are shown separately wherever possible. That prevents a misleading single pence-per-kWh figure.
Worked example in pounds
At 26.11p/kWh, a constant 1 kW load costs 26.11p an hour.
The example checks the method. It is not a universal tariff or a forecast of your next bill.
What changes the result
The largest differences usually come from:
- actual draw
- thermostat cycles
- duration
- time-of-use rate
- VAT
How to improve the estimate
Use rates for your region, payment method and meter, including VAT consistently. Match the number of days and do not add standing charges or discounts twice.
Use actual meter readings, separate electricity from gas and compare at least a year for weather-sensitive use. Keep debt repayments and account credit outside consumption cost.
Pre-filled figures are editable, dated reference values with a source.
Frequently asked questions
Will this match my energy bill?
Not necessarily. Regional rates, price changes inside a bill, meter estimates, tariff discounts, debt and rounding can differ.
Does the price cap limit my total bill?
No. It limits rates for covered default tariffs; total cost still rises with energy use.
Sources and review date
Content reviewed on: 2026-08-03.
- Ofgem – price cap rates, 1 July to 30 September 2026 — average unit rates, standing charges and regional tables