Joule to Kilojoule Converter
Convert joules to kilojoules instantly with an energy calculator built for science, nutrition, HVAC, electricity, engineering, and everyday reference.
J to kJ Calculator
Enter an energy value and the conversion updates automatically.
Result updates automatically.
Formula: kilojoules = joules × 0.001
How to Convert Joule to Kilojoule
Energy conversion uses joules as the SI reference unit. Multiply the source energy by the factor shown below to convert it into the selected output unit.
1 joule
0.001 kilojoules
10 joules
0.01 kilojoules
100 joules
0.1 kilojoules
Energy Formula Notes
The calculator converts through joules as the base energy unit, then formats the result for the selected energy unit.
Joules to kJ Converter FAQ
Which energy units are supported?
This tool supports joules, kilojoules, BTU, small calories, kilocalories, watt-hours, kilowatt-hours, foot-pounds, and newton-meters.
How do I convert J to kJ?
Multiply the J value by 0.001 to get kJ. The calculator performs the formula automatically.
Can I reverse the energy conversion?
Yes. Use the swap button to reverse the selected units and calculate the opposite direction.