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Watts to kWh Calculator: Kilowatt-Hours by Run Time

Convert watts to kilowatt-hours, or kWh back to watts, by setting how long the load runs. kWh is the energy unit your utility bills, so this turns an appliance's wattage into the energy it uses. To put a dollar figure on it, jump to the electricity cost calculator. Just converting the power unit (W to kW)? Use the watts to kilowatts converter instead.

Convert

Energy used

6 kWh

Power
1,500 W
Over
4 h
If daily, per month
180 kWh

Energy (kWh) = power (W) × hours ÷ 1,000. To turn kWh into a dollar figure at your electricity rate, use the electricity cost calculator linked below.

Measure kilowatt-hours directly

Kilowatt-hours are what the utility bills, and converting to them means knowing the watts and the hours. A meter counts them instead. A plug-in energy meter measures one corded 120 V appliance; a whole-home monitor's sensors clip on inside the panel and log every circuit.

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Frequently asked questions

Kilowatt-hours = watts × hours ÷ 1,000. A watt is a rate of power; a kilowatt-hour is energy used over time. Example: a 1,500-watt heater running 4 hours uses 1,500 × 4 ÷ 1,000 = 6 kWh.

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WattSimple. (2026, July 19). Watts to kWh Calculator: Kilowatt-Hours by Run Time. https://wattsimple.com/convert/watts-to-kwh

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"Watts to kWh Calculator: Kilowatt-Hours by Run Time." WattSimple, 19 July 2026, https://wattsimple.com/convert/watts-to-kwh.

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WattSimple. "Watts to kWh Calculator: Kilowatt-Hours by Run Time." Last modified July 19, 2026. https://wattsimple.com/convert/watts-to-kwh.

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<a href="https://wattsimple.com/convert/watts-to-kwh">Watts to kWh Calculator: Kilowatt-Hours by Run Time</a> (WattSimple)

Sources & standards

This tool's methodology and data follow US standards and authoritative public datasets: