Kilowatt-hours to Joules Converter

How it is calculated

The conversion is a single multiplication: J = kWh × 3,600,000 and MJ = kWh × 3.6. It is exact, because 1 kW is 1000 J/s and 1 hour is 3600 s, so 1 kWh = 1000 × 3600 = 3,600,000 J. Joules are rounded to a whole number and megajoules to two decimals, so a very small input loses detail in the MJ line: 0.0001 kWh shows 360 J but 0.00 MJ. Use the joule line for small amounts. The tool accepts any number, including zero and negatives, and does not check that a value is realistic. The input is energy in kWh, not power in kW; the time already sits inside the unit.

Common mistakes

• Entering a power in kW (such as a 2 kW heater) as if it were an energy in kWh; you also need the running time, and kW × hours gives the kWh to enter.
• Mixing up kWh with kW or with watts per hour; kWh is already energy, so there is no further division by time.
• Confusing kilojoules and megajoules when reading the result: 1 kWh is 3,600 kJ or 3.6 MJ, not 3.6 kJ.
• Reading 0.00 MJ for a tiny input as zero energy; the joules line still shows the real value.
• Using the 3,600,000 factor for calories or BTU questions; those need other units.