Joule to Kilojoule Conversion

Convert between Joule and Kilojoule quickly and accurately.

J
kJ

How to Convert Joule to Kilojoule

Conversion Formula

1 J = 0.001 kJ
1 kJ = 1000 J

Example

Convert 15 J to kJ:

15 J = 15 × 0.001 kJ = 0.015 kJ

Unit Information

Learn about the energy units you're converting between

Joule

J

Definition

The joule (symbol: J) is the SI base unit of energy, work, and heat. It is defined as the work done when a force of one newton moves an object one meter in the direction of the force. One joule equals one newton-meter or one watt-second.

History/Origin

The joule was named after James Prescott Joule (1818-1889), an English physicist who established the mechanical equivalent of heat. It was officially adopted as the SI unit of energy in 1948, replacing the calorie in scientific contexts.

Current Use

Joules are used universally in physics, engineering, and chemistry for measuring energy, work, and heat. Applications include electrical energy calculations, mechanical work, thermal energy, and energy efficiency measurements in all scientific and industrial fields.

Multiplier

1

Offset

0

Kilojoule

kJ

Definition

A kilojoule (symbol: kJ) is a unit of energy equal to 1,000 joules. It is commonly used for measuring larger amounts of energy in food, exercise, and industrial applications. One kilojoule equals approximately 0.239 kilocalories.

History/Origin

The kilojoule was introduced as a practical unit for measuring larger energy quantities in the metric system. It became widely used in the late 20th century for food labeling and energy consumption measurements.

Current Use

Kilojoules are extensively used in nutrition labeling worldwide, exercise physiology for measuring energy expenditure, industrial energy consumption monitoring, and scientific research for measuring moderate energy quantities.

Multiplier

1000

Offset

0

Joule to Kilojoule Conversion Table

Joule [J] Kilojoule [kJ]
1 J 0.001 kJ
10 J 0.01 kJ
25 J 0.025 kJ
50 J 0.05 kJ
100 J 0.1 kJ
0 J 0E+0 kJ
-10 J -0.01 kJ
-40 J -0.04 kJ

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