Battery Equivalents and Replacements

Calories (cal) to Kilojoules (kJ) Conversion Calculator and Table

Calories (cal) and kilojoules (kJ) are units of energy, and their conversions are simple and straightforward - one just has to remember that "k" stands for "kilo," which is, according to the SI prefixes table, 103 (one thousand) of the main value. Also, the calorie, as a unit of energy, is tied to the energy required to increase or decrease the temperature of water.

Published: January 10, 2024.

To convert calories to kilojoules, write the value in calories and click 'Calculate':

Calories (cal) to Kilojoules (kJ)

Calories (cal):

Kilojoules (kJ):

To convert kilojoules to calories, check our Kilojoules (kJ) to Calories (cal) Conversion Calculator and Table article.

How To Convert Calories (cal) to Kilojoules (kJ)

"k" stands for "kilo" and means "one thousand."  Thus, one kilojoule equals 1000 joules:

1kJ = 1000J

Also, there are "two" types of calories which describe energy - these are:

  • Small calorie (cal): energy required to increase 1 gram (1g) of water by 1°C at normal/standard conditions (room temperature (20°C), 1 atmosphere pressure). Small calorie (cal) is also known as thermochemical calorie.
  • Large calorie (Cal): energy required to increase 1 kilogram (1 kg) of water by 1°C at normal/standard conditions (room temperature (20°C), 1 atmosphere pressure). Large calorie (Cal) is known as "food calorie."

The relation between small calorie (cal) and large calorie (Cal) is:

1 Cal = 1000 cal = 1 kcal

Unless otherwise noted, whenever discussing calories, we are discussing/talking about small calories (cal).

The relationship between small calories and kilojoules is as follows:

1 kJ = 1/0.004184 cal = ~239.0057361376 cal = ~239 cal

1 cal = 4.184 J = 0.004184 kJ

For example, if You want to convert 15.34 cal to kJ, You can write:

E(cal) = 15.34 cal = 15.34 * 0.004184 kJ = 0.06418256 kJ = 64.18256 joules (J)


Calories (cal) to Kilojoules (kJ) Conversion Table

The following chart contains the most common Kilojoules (kJ) values converted to calories (cal):

Calories (cal) Kilojoules (kJ)
1 0.004184
10 0.04184
50 0.2092
100 0.4184
500 2.092
1000 4.184
2000 8.368
3000 12.552
5000 20.92
10000 41.84
100000 418.4


If You wish to convert values that are not in the table, please use the calories to kilojoules conversion calculator.

Quick Intro to Joules

The joule, symbolized as 'J', is a fundamental unit of energy in the International System of Units (SI). It is a crucial measurement in various scientific and technical fields, encompassing physics, engineering, and beyond.

One joule is defined as the amount of energy expended when a force of one newton is applied over a distance of one meter. This definition ties the joule directly to basic physical concepts of force and distance, making it integral to understanding energy dynamics in a scientific context.

The origin of the joule dates back to the 19th century and is named after the English physicist James Prescott Joule. His pioneering work in the field of thermodynamics, particularly his studies on the relationship between heat, work, and temperature, laid the foundation for modern energy concepts.

Joule's experiments, which demonstrated the conversion of mechanical work into heat, led to the formulation of the first law of thermodynamics and established the groundwork for the energy conservation principle.

In practical applications, the joule is a versatile unit. It is used to quantify energy in various forms, including the kinetic energy of moving objects, the potential energy stored in objects, and the energy transferred in electrical and thermal processes.

For example, in the electrical domain, one joule is the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second.

The joule's significance extends beyond scientific calculations. It is also a key unit in everyday life, particularly in understanding and measuring energy consumption and efficiency. For instance, the energy usage of electrical appliances is often rated in joules or kilojoules (1,000 joules), providing a clear metric for energy consumption.

Quick Intro To Calories

The calorie, a unit of energy measurement, is integral to various fields, particularly nutrition and biochemistry. Defined as the amount of heat required to raise the temperature of one gram of water by one degree Celsius, the calorie provides a basic measure of energy in both food and physical processes.

The concept of the calorie originated in the early 19th century, with the work of French chemist Nicolas Clément playing a pivotal role. Initially used in the context of heat and thermodynamics, the calorie was adopted into the nutritional sciences as a measure of the energy content in food. This transition marked the calorie's evolution from a purely scientific term to a key component in dietary and health-related discussions.

In nutritional contexts, the term "calorie" usually refers to what is technically a kilocalorie (kcal), equivalent to 1,000 small calories. This larger unit, often called the dietary or food calorie, is denoted with a capital 'C' (Cal) to differentiate it from the smaller calorie (cal). The dietary Calorie (Cal) is the standard measurement used on food labels in many countries, reflecting the energy that food provides to the body when consumed.

The distinction between the small calorie (cal) and the dietary Calorie (Cal) is essential for accuracy in both scientific and everyday language. The small calorie is relevant in fields like chemistry and physics for measuring small amounts of energy, whereas the dietary Calorie is practical in nutrition and dietetics, where larger energy quantities are more common. This differentiation ensures clarity, particularly in dietary planning and nutritional education.

Understanding the calorie is crucial for professionals in nutrition, health, and fitness, as well as for individuals mindful of their energy intake and expenditure. As a fundamental measure of energy, the calorie is central to grasping how the body processes food and how different foods contribute to energy needs. Its widespread use in both scientific and public spheres underscores its importance in our daily lives.