How UK electricity running costs are calculated
Appliance energy consumption is calculated by multiplying power in watts by daily operating hours and dividing by 1,000 to obtain kilowatt-hours (kWh).
The kWh consumption is multiplied by your electricity unit rate in pence per kWh under the Ofgem Energy Price Cap, with optional daily standing charges.
Worked example
For a 2,000-watt domestic heater running 3 hours a day, 7 days a week, at the standard UK price cap unit rate of 24.5p per kWh:
Daily consumption is 6 kWh. At 24.5p/kWh, the heater costs £1.47 per day, approximately £44.59 per month and £535.08 per year to operate.
Inputs for the electricity cost calculator
Appliance power rating
Power consumption of the appliance in watts (W), listed on the rating label.
Usage hours per day
Average hours the appliance is actively powered on each day.
Days used per week
Number of operating days per week from 1 to 7.
Electricity rate (pence per kWh)
Your domestic electricity rate in pence per kilowatt-hour under the Ofgem price cap.
Daily standing charge (optional)
Fixed daily connection fee charged on your UK electricity bill.
CALCULATOR QUESTIONS
Electricity cost calculator questions
What is the Ofgem Energy Price Cap?
The price cap is set by the UK energy regulator Ofgem and limits the maximum unit rate and standing charge suppliers can bill on standard variable tariffs.
How do I find the wattage of my appliance?
Check the rating plate or label on the back or underside of the device, which displays the power rating in watts (W) or kilowatts (kW).