Joule vs. Calorie — What's the Difference?
By Tayyaba Rehman — Updated on September 19, 2023
A "joule" is the SI unit of energy, used universally in science and engineering. A "calorie" is also a unit of energy but is mainly used in nutrition and food science. One calorie is equivalent to approximately 4.184 joules.
Difference Between Joule and Calorie
Table of Contents
ADVERTISEMENT
Key Differences
A "joule" is the standard unit of energy in the International System of Units (SI), commonly used in physics, engineering, and various scientific disciplines. A "calorie," on the other hand, is a unit of energy often used to quantify energy content in food or metabolic rates in biology and nutrition. While both are units of energy, their applications differ significantly.
In terms of equivalence, one calorie is approximately 4.184 joules. It's important to note that the term "calorie" used in nutritional labeling in the United States is actually a "kilocalorie," or 1000 small calories, and thus equivalent to approximately 4184 joules. This creates a bit of a discrepancy and can lead to confusion, particularly for those transitioning from one field to another.
Grammatically, both "joule" and "calorie" are nouns and can be made plural by adding an "s" at the end ("joules," "calories"). They are both named after people: the term "joule" is named after the British physicist James Prescott Joule, while "calorie" is derived from the Latin word "calor," meaning heat, although it honors no specific individual.
When discussing thermal energy or heat transfer in scientific contexts, "joules" are generally preferred. In contrast, "calories" are favored in discussions about nutrition, diet, and metabolism. Thus, while both units measure energy, the fields in which they are primarily used are quite distinct. The distinction helps maintain clarity in scientific and public discourse.
Comparison Chart
Main Usage
General Science
Nutrition, Food Science
ADVERTISEMENT
Value
Universal
Approx. 4.184 Joules
Named After
James Prescott Joule
Derived from "calor"
Plurals
Joules
Calories
Special Forms
MegaJoules, KiloJoules
KiloCalories
Compare with Definitions
Joule
The standard unit of energy in the International System of Units.
The car consumes 500,000 joules of energy per mile.
Calorie
Equivalent to approximately 4.184 joules.
One calorie is roughly 4.184 joules of energy.
Joule
The energy unit used in various scientific and engineering contexts.
The electric heater uses 2000 joules per second.
Calorie
Used to quantify the metabolic energy required to raise the temperature of one gram of water by one degree Celsius.
It takes one calorie to heat one gram of water by one degree Celsius.
Joule
A measure of work done when a force of one newton is applied over a distance of one meter.
Lifting the box required 50 joules of energy.
Calorie
Sometimes refers to "kilocalories" in food labeling and nutritional information.
A food label stating 200 calories actually means 200 kilocalories or 200,000 small calories.
Joule
Equivalent to the heat required to raise the temperature of one gram of water by 0.239 degrees Celsius.
It takes 4200 joules to boil a liter of water.
Calorie
A unit of energy commonly used to measure food energy.
An apple contains about 95 calories.
Joule
A derived metric unit named after physicist James Prescott Joule.
Joules are named after a British physicist who contributed to thermodynamics.
Calorie
Often used in dietary and nutritional contexts.
Cutting 500 calories a day can lead to weight loss.
Joule
The joule ( jowl, jool; symbol: J) is a derived unit of energy in the International System of Units. It is equal to the energy transferred to (or work done on) an object when a force of one newton acts on that object in the direction of the force's motion through a distance of one metre (1 newton-metre or N⋅m).
Calorie
The calorie is a unit of energy defined as the amount of heat needed to raise the temperature of a quantity of water by one degree. For historical reasons, two main definitions of calorie are in wide use.
Joule
The International System unit of electrical, mechanical, and thermal energy, equal to the work done when a force of one newton acts through a distance of one meter, and also equal to the work done when a current of one ampere is passed through a resistance of one ohm for one second.
Calorie
Abbr. cal Any of several approximately equal units of heat, each measured as the quantity of heat required to raise the temperature of 1 gram of water by 1°C at 1 atmosphere pressure. Also called gram calorie, small calorie.
Joule
In the International System of Units, the derived unit of energy, work and heat; the work required to exert a force of one newton for a distance of one metre. Equivalent to one watt of power for a duration of one second. Symbol: J
Calorie
Abbr. cal The unit of heat equal to 1/100 the quantity of heat required to raise the temperature of 1 gram of water from 0 to 100°C at 1 atmosphere pressure. Also called mean calorie.
Joule
A unit of work which is equal to 107 ergs (the unit of work in the C. G. S. system of units), and is equivalent to one watt-second, the energy expended in one second by an electric current of one ampere in a resistance of one ohm; also called the absolute joule. It is abbreviated J or j. The international joule is slightly larger, being 1.000167 times the absolute joule. The absolute joule is approximately equal to 0.737562 foot pounds, 0.239006 gram-calories (small calories), and 3.72506 x 10-7 horsepower-hours, and 0.000948451 B.t.u.
Calorie
Abbr. Cal The unit of heat equal to the amount of heat required to raise the temperature of 1 kilogram of water by 1°C at 1 atmosphere pressure. Also called kilocalorie, kilogram calorie, large calorie.
Joule
A unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second
Calorie
A unit of energy-producing potential equal to this amount of heat that is contained in food and released upon oxidation by the body. Also called nutritionist's calorie.
Joule
English physicist who established the mechanical theory of heat and discovered the first law of thermodynamics (1818-1889)
Calorie
(nutrition) Kilogram calorie or large calorie. A unit of energy 1000 times larger than the gram calorie. It is equivalent to the gram kilocalorie, approximately 4.2 kilojoules.
Calorie
The gram calorie or small calorie, a non-SI unit of energy, equivalent to approximately 4.2 joules. This unit was widely used in chemistry and physics, being the amount of energy needed to raise the temperature of 1 gram of water by 1 °C.
Calorie
The unit of heat according to the French standard; the amount of heat required to raise the temperature of one kilogram (sometimes, one gram) of water one degree centigrade, or from 0° to 1°. Compare the English standard unit, Foot pound.
Calorie
Unit of heat defined as the quantity of heat required to raise the temperature of 1 gram of water by 1 degree centigrade at atmospheric pressure
Calorie
A unit of heat equal to the amount of heat required to raise the temperature of one kilogram of water by one degree at one atmosphere pressure; used by nutritionists to characterize the energy-producing potential in food
Common Curiosities
Is a food Calorie the same as a scientific calorie?
No, a food Calorie is actually a kilocalorie, equivalent to 1000 scientific calories or about 4184 joules.
What is a Calorie?
A calorie is a unit of energy mainly used in food science and nutrition.
What is a Joule?
A joule is the standard unit of energy in the International System of Units, used in various scientific contexts.
Which is used more universally, Joules or Calories?
Joules are more universally used across scientific disciplines.
When should I use Calories?
Use calories in nutritional and food-related contexts.
Are both terms named after someone?
Joule is named after James Prescott Joule; calorie is derived from the Latin word "calor," meaning heat.
When should I use Joules?
Use joules in scientific, engineering, and general energy contexts.
Are Joules and Calories interchangeable?
Yes, but they are used in different fields; one calorie is approximately 4.184 joules.
Can you pluralize both words?
Yes, joules and calories.
Is Calorie capitalized?
In food science, the term is often capitalized to indicate kilocalories.
Is Calorie a precise unit?
It is precise in its field but less universal than joules.
What is the symbol for Joule?
The symbol for joule is 'J'.
Are both Joule and Calorie metric units?
Yes, both are metric units of energy.
Can Joules and Calories be converted?
Yes, one calorie is approximately 4.184 joules.
What is the symbol for Calorie?
The symbol for calorie is 'cal', but it can differ in nutritional contexts.
Share Your Discovery
Previous Comparison
Aspiration vs. Inspiration
Next Comparison
Automatic vs. AutomatedAuthor Spotlight
Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
