Watts into energy
Watts to kWh calculator
Convert electrical power and operating time into kilowatt-hours, then see daily, period, and annual totals.
How to convert watts to kilowatt-hours
Watts measure power, while kilowatt-hours measure energy used over time. A duration is therefore required: watts alone cannot be converted to kWh.
Watts to kWh formula
Energy (kWh) = power (W) × time (hours) ÷ 1,000. Convert minutes to hours first; for example, 30 minutes is 0.5 hours.
A quick unit check
1,000 W for 1 hour is 1 kWh. The same energy is used by 100 W for 10 hours: 100 × 10 ÷ 1,000 = 1 kWh.
Default worked example
The calculator starts with 1,500 W for 3 hours: 1,500 × 3 ÷ 1,000 = 4.5 kWh per use. It then scales that energy by quantity, uses, and days.
Use measured or realistic power
A nameplate wattage may not equal average power when a device cycles or changes load. This page estimates energy from the values entered; it does not size wiring, protection, components, or certify electrical safety.
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