Electricity cost calculator
Enter an appliance's wattage, how long it runs and your unit rate. Get kWh, period cost and a 30-day estimate instantly.
Electricity cost formula
Electrical power is usually shown in watts (W). Bills charge for energy in kilowatt-hours (kWh), so first convert watts to kilowatts and multiply by time.
Cost: kWh × price per kWh = usage cost
Worked example
A 1,000 W appliance running for 2 hours uses 2 kWh. If your unit price is €0.30/kWh, the usage cost is €0.60. Repeat the same use on 30 days and the usage portion totals €18.00.
What this estimate does not include
Electricity bills may contain fixed charges, taxes, network charges or time-of-use prices. If those costs are not already included in the unit rate you enter, they are outside this appliance-level estimate.
Frequently asked questions
What if my appliance changes power while running?
Use average measured power or measured kWh over a typical session. Maximum rated power is useful as a conservative estimate but may not reflect cycling or variable loads.
Can I use this with pounds, euros or other European currencies?
Yes. The calculation is currency-neutral; the selector only changes how the result is displayed.
Is 1,000 watts the same as 1 kWh?
No. 1,000 watts is power. A 1,000 W device running for one hour uses 1 kWh of energy.