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This calculator estimates how much an electrical appliance costs to run. It converts the appliance's power rating and how long you use it into energy in kilowatt-hours (kWh), then multiplies by your electricity tariff.
Use it to compare appliances, judge the impact of an always-on device, or budget a monthly electricity bill for a single load.
One kilowatt-hour (unit) is 1000 watts running for one hour. Dividing watts by 1000 converts the power to kilowatts before multiplying by time.
It is usually printed on a rating label, the nameplate, or in the manual. If only current and voltage are given, multiply them: watts = volts × amps.
A kilowatt-hour is the energy used by a 1000 W appliance running for one hour. Electricity bills charge per kWh, which utilities often call a 'unit'.
Not necessarily — cost depends on wattage and running time together. A 2000 W kettle used for 5 minutes can cost far less than a 40 W bulb left on all day.
Real usage hours vary, tariffs can be tiered or include fixed charges and taxes, and thermostat-controlled devices do not draw full power continuously. Treat the result as a close estimate.