Electric Heater Running Cost Calculator UK
Estimate the running cost of an electric heater using its wattage, hours used per day and your electricity rate.
The calculator defaults to 26.11p per kWh, the Ofgem average electricity unit rate for a standard variable tariff paid by Direct Debit from 1 July to 30 September 2026. Your own tariff may be different.
View Ofgem electricity rates →Calculate Running Cost
Your Estimated Running Costs
Usage Summary
Estimated annual use: —
Estimated electricity use per year: —
How is the cost calculated?
The calculator converts watts to kilowatts and multiplies that by the hours used. This gives estimated electricity consumption in kWh.
If the device's power draw changes during use, a measured average wattage will usually give a better estimate than its maximum rating.
Frequently Asked Questions
Does a 2 kW heater always use 2 kWh every hour?
If it draws 2 kW continuously for a full hour, that equals 2 kWh. Thermostatic heaters may switch on and off, reducing actual consumption.
Why can thermostats change the result?
Once a room reaches the target temperature, some heaters cycle off and on instead of drawing full power continuously.
Can I compare different heater sizes?
Yes. Enter each heater's rated wattage and the same usage pattern to compare simple maximum-power estimates.
Other Electricity Cost Calculators
Compare other household appliances using the same electricity rate. See how to compare running costs fairly.