How To Calculate Appliance Electricity Cost
Reference table
| 500W for 1 hour | 0.5 kWh | 12.34p |
|---|---|---|
| 1,000W for 1 hour | 1 kWh | 24.67p |
| 2,000W for 1 hour | 2 kWh | 49.34p |
What to know
First convert watts to kilowatts by dividing by 1,000.
Practical guidance
Then multiply by the number of hours the appliance is running.
How to use this
Finally multiply by the electricity price in pence per kWh. Use your own tariff for the most accurate answer.
FAQs
What is the formula?
Watts ÷ 1,000 × hours × pence per kWh.
What if I only know kWh?
Multiply kWh directly by the pence-per-kWh rate.
Does wattage always equal real use?
No. Thermostats, motors and cycles can reduce average power.
Where do I find wattage?
Check the appliance label, manual or energy meter.
Last reviewed 3 May 2026. Source: Ofgem energy price cap. Figures are estimates. Actual prices vary by region, supplier, tariff, payment method and meter type.