Watts to kWh Calculator

Convert power consumption in Watts (W) to energy in Kilowatt-hours (kWh).

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How to Convert Watts to kWh

To convert Watts to Kilowatt-hours, you need to divide the power in Watts by 1000 to get Kilowatts, and then multiply by the time in hours.

Formula

E(kWh) = (P(W) × t(h)) / 1000

Calculation Example

Question: A 100 Watt light bulb is on for 10 hours. How much energy does it use?

Answer:
E = (100 W × 10 h) / 1000 = 1 kWh

Common Appliance Energy Usage

Appliance Power (Watts) Time Energy (kWh)
LED Bulb10 W24 hours0.24 kWh
TV100 W5 hours0.5 kWh
Heater1500 W2 hours3.0 kWh