Convert an appliance’s power in watts into the kilowatt-hours (kWh) you are billed for, per hour, day, month and year. Then see what it costs in one click.
Watts to kWh calculator
Convert an appliance’s watts into the kilowatt-hours you are billed for.
kWh = watts ÷ 1,000 × hours. A 1,500 W appliance running for one hour uses 1.5 kWh.
Energy per month
–
- Per hour
- –
- Per day
- –
- Per year
- –
- Kilowatts
- –
Need the cost straight away? The appliance cost calculator does both steps.
The formula
kWh = watts ÷ 1,000 × hours. A 100 W TV on for 5 hours uses 0.5 kWh; a 2,000 W heater on for 3 hours uses 6 kWh.
Where to find the watts
- On the rating label or plate, usually on the back or underneath.
- In the manual or the manufacturer’s website.
- If only amps are shown, multiply by the voltage: about 120 V in the US and 230 V in the UK. 10 amps at 120 V is about 1,200 W.
- For appliances that cycle on and off, a plug-in energy meter gives the real figure.