Joule [J] to Kilojoule [kJ] Converter

Quick Reference

1 Joule (J) = 0.001 Kilojoule (kJ)

1 Kilojoule (kJ) = 1000 Joule (J)

How to Convert Joule to Kilojoule

1 J = 0.001 kJ
1 kJ = 1000 J

To convert Joule to Kilojoule, divide the value by 1000 (equivalently, multiply by 0.001). To convert Kilojoule back to Joule, multiply by 1000.

Example: convert 10 J to kJ:
10 J = 10 x 0.001 = 0.01 kJ

↔ Convert Kilojoule to Joule

Joule

Definition: The joule (symbol: J) is the SI derived unit of energy. It is defined as the energy transferred to (or work done on) an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre (1 newton metre or N⋅m).

History/origin: Named after James Prescott Joule, an English physicist. Joule experimentally determined the mechanical equivalent of heat.

Current use: Used universally in science and engineering to quantify energy, work, and heat. Examples include kinetic energy, potential energy, and heat content of materials.

Kilojoule

Definition: A kilojoule (symbol: kJ) is equal to 1000 joules. It's a unit of energy.

History/origin: Based on the joule, using the SI prefix 'kilo-' to denote a factor of one thousand.

Current use: Commonly used to express the energy content of food, fuels, and other substances when the joule would be impractically small. Also used in thermodynamics and other areas of physics and engineering.

Joule to Kilojoule Conversion Table

Joule [J]	Kilojoule [kJ]
1 J	0.001 kJ
2 J	0.002 kJ
5 J	0.005 kJ
10 J	0.01 kJ
20 J	0.02 kJ
50 J	0.05 kJ
100 J	0.1 kJ
200 J	0.2 kJ
500 J	0.5 kJ
1000 J	1 kJ

Common pairs of Energy

Watt-hour

Watt-hour to Milliwatt-hour Watt-hour to Kilowatt-hour Watt-hour to Megawatt-hour Watt-hour to Gigawatt-hour Watt-hour to Joule

Milliwatt-hour

Milliwatt-hour to Watt-hour Milliwatt-hour to Kilowatt-hour Milliwatt-hour to Megawatt-hour Milliwatt-hour to Gigawatt-hour Milliwatt-hour to Joule

Kilowatt-hour

Kilowatt-hour to Watt-hour Kilowatt-hour to Milliwatt-hour Kilowatt-hour to Megawatt-hour Kilowatt-hour to Gigawatt-hour Kilowatt-hour to Joule

Megawatt-hour

Megawatt-hour to Watt-hour Megawatt-hour to Milliwatt-hour Megawatt-hour to Kilowatt-hour Megawatt-hour to Gigawatt-hour Megawatt-hour to Joule

Gigawatt-hour

Gigawatt-hour to Watt-hour Gigawatt-hour to Milliwatt-hour Gigawatt-hour to Kilowatt-hour Gigawatt-hour to Megawatt-hour Gigawatt-hour to Joule

Joule

Joule to Watt-hour Joule to Milliwatt-hour Joule to Kilowatt-hour Joule to Megawatt-hour Joule to Gigawatt-hour

Kilojoule

Kilojoule to Watt-hour Kilojoule to Milliwatt-hour Kilojoule to Kilowatt-hour Kilojoule to Megawatt-hour Kilojoule to Gigawatt-hour

Joule [J] to Kilojoule [kJ] Converter

To convert Joule to Kilojoule, enter your value in the J field above and the result in kJ will appear instantly. You can also use the conversion factor shown in the table on this page to calculate manually. The formula is always the same: multiply your J value by the fixed conversion ratio to get the equivalent in kJ.

Our Joule to Kilojoule converter uses standardized conversion factors defined by international scientific and metrological organizations. All calculations are performed with full floating-point precision. You can also choose how many decimal places to display in the result, so you get exactly the level of detail you need.

Yes, absolutely. Simply swap the source and destination units in the converter — select kJ as your input unit and J as your output unit. The same precision and standardized conversion factor applies in both directions.

Converting between Joule and Kilojoule comes up regularly in engineering, scientific research, construction, and everyday tasks that involve measurements from different unit systems. Our converter eliminates the risk of manual calculation errors and saves time whenever you need to switch between these two units.

Yes, the Joule to Kilojoule converter is completely free. No account or registration is required, and there are no usage limits. It works on any device — smartphones, tablets, and desktop computers — directly in your browser.

Joule and Kilojoule are both units used to measure the same physical quantity, but they belong to different measurement systems or represent different scales. The mathematical relationship between them is fixed and constant, which is what makes accurate conversion possible. Scroll up to see the exact conversion factor, formula, and a reference table for common values.

Joule [J] to Kilojoule [kJ] Converter

Quick Reference

1 Joule (J) = 0.001 Kilojoule (kJ)

1 Kilojoule (kJ) = 1000 Joule (J)

How to Convert Joule to Kilojoule

1 J = 0.001 kJ
1 kJ = 1000 J

To convert Joule to Kilojoule, divide the value by 1000 (equivalently, multiply by 0.001). To convert Kilojoule back to Joule, multiply by 1000.

Example: convert 10 J to kJ:
10 J = 10 x 0.001 = 0.01 kJ

↔ Convert Kilojoule to Joule

Joule

History/origin: Named after James Prescott Joule, an English physicist. Joule experimentally determined the mechanical equivalent of heat.

Current use: Used universally in science and engineering to quantify energy, work, and heat. Examples include kinetic energy, potential energy, and heat content of materials.