Watts measure power (the rate of energy use), but joules measure the actual energy consumed over time — and the Watts to Joules Calculator converts between the two. Enter your Power (W) and Time (s) to get your Energy in Joules, plus equivalent values in kilowatt-hours (kWh) and calories (cal).
Energy (J)
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Energy (kWh)
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Energy (cal)
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To convert watts to joules, multiply the power in watts by the time in seconds. The formula is: Energy (J) = Power (W) × Time (s). For example, 100 watts for 60 seconds equals 6,000 joules.
Watts measure power (energy per unit time), while joules measure energy. Watts tell you the rate of energy consumption, and joules tell you the total amount of energy used over a specific time period.
Because watts are a rate of energy consumption per second, you need to specify the duration to calculate the total energy consumed. Without time, you cannot determine the total energy in joules.
Yes, to convert joules to watts, divide the energy in joules by the time in seconds: Power (W) = Energy (J) ÷ Time (s). This gives you the average power consumption over that time period.
This conversion is useful for calculating energy consumption of electrical devices, battery capacity requirements, heating calculations, and determining electricity costs based on power ratings and usage time.
One kilowatt-hour (kWh) equals 3,600,000 joules. This is because 1 kW = 1,000 W and 1 hour = 3,600 seconds, so 1,000 W × 3,600 s = 3,600,000 J.