Watts to kWh
kWh = (W ÷ 1,000) × hours × load factor. Multiply kWh by your electricity price to estimate energy cost.
♨️ Worked example
How much electricity does an electric radiator use?
Log room setpoint and outdoor conditions. Replace example inputs with your own usage pattern.
6.30 kWhper day of use
37.80 €per month at 0.20 €/kWh
Worked example
1500 W × 6 h/day × 70 % load factor × 30 days.
189.00 kWh/month · 453.60 €/year
This is an energy-only estimate. Your bill can also include standing charges, taxes and other household consumption.
Typical reference range
Use the label, manual or manufacturer data for your exact model whenever possible.
| Type or situation | Indicative reference |
|---|---|
| Small room | 500–1,000 W |
| Typical radiator | 1,000–1,500 W |
| Large room | 1,500–2,500 W |
What changes the result?
Rated watts are only one part of the calculation.
Measure when possible
Thermostats, compressors, inverter control and programmes can make real consumption lower or higher than a simple maximum-power estimate.
Practical checks
- Thermostat duty cycle matters more than the name on the heater.
- Reduce heat loss before increasing heater size.
- Compare direct electric heating with a heat pump for long daily use.
Quick answer
Electric radiator electricity use: watts, time and thermostat
Electric radiator electricity use depends on rated power, running time and how often the thermostat cycles the heater on and off. Use the radiator’s input power and realistic operating time for an estimate, then compare the result with measured consumption whenever possible.
Compare more appliances
Return to the appliance library or use the general electricity calculator for any device.
NEXT STEP
Keep exploring
Thermostat duty cycle is the key variable
A 1,500 W electric radiator does not necessarily consume 1.5 kWh every hour it is switched on. Once the room reaches the set temperature, the thermostat may cycle the heating element on and off. The average duty cycle depends on heat loss, outdoor temperature, room size and thermostat setting.
Room heat loss matters more than heater branding
Direct electric resistance heaters convert electrical energy into heat at the point of use in broadly similar ways. What often changes the monthly bill most is how long the heater has to run to replace heat escaping through walls, windows, air leakage and ventilation.
Compare systems for long daily use
If heating is used for many hours each day, compare the result with a heat pump rather than looking only at radiator purchase price. See electric radiator vs heat pump and test different scenarios with the electricity consumption calculator.
For Spain, use the current electricity price when converting kWh into cost.
Editorial review: 11 Oct 2026. Actual runtime depends strongly on weather, insulation and thermostat behaviour.
BRICODATO · PRACTICAL CHECK
Check the real energy use of your electric radiator
For resistance heaters, room heat loss and thermostat runtime drive kWh. Cycling off at a setpoint lowers active time, but resistance heating is not the same conversion as a heat pump. Insulation, target temperature and heated area strongly affect an hourly-cost estimate.
Checklist to reproduce the comparison
- Log room setpoint and outdoor conditions.
- Separate plugged-in hours from actual heater-on hours.
- Compare technologies under the same comfort target and room conditions.
The figures elsewhere on this page are illustrative assumptions, not a measured average for every model. Use the label, your actual cycle count and safely collected kWh readings.