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 a electric radiator use?
Start with a transparent example, then replace the assumptions with your own wattage, operating time and electricity price.
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.
Compare more appliances
Return to the appliance library or use the general electricity calculator for any device.
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