Calories are the amount of energy in foods and beverages, or the amount of energy you burn exercising.
Energy is measured in Kilocalories (kcal) and kilojoules (kJ). If you&#39;re counting calories or comparing the calorie contents of foods, this can cause confusion.

Calories are a measure of energy

Calories can be small or large.
<ul>
<li>A large calorie estimates the amount of energy needed to raise the temperature of 1 kg (2.2 pounds) of water by 1°C (34°F).</li>
<li>A small calorie estimates the amount of energy it takes to raise the temperature of 1 gram (0.035 ounces) of water by 1°C (34°F)</li>
</ul>
This means that 1 large calorie = 1,000 small calories, as 1 kg = 1,000 grams.

Small and large calories

The term kilocalorie (kilo meaning 1,000) was created to refer to a large calorie. The term small calorie is only used in physics and chemistry research.
This means that with nutrition, the terms calories and kcal equal the same amount of energy (1 kilokalorie = 1 calorie in nutrition.)

1 kilocalorie = 1 calorie in nutrition

One calorie (kcal) = 4.18 kJ
To convert from calories to kJ, multiply calories by 4.18.
For example, a medium-sized banana (118 grams) provides 105 calories (kcal). 105 x 4.18 = 439 kJ.

To convert from calories to kJ

Calories are a measure of energy. They refer to the amount of energy in foods and beverages, or the amount of energy you burn exercising.Depending on where you live, energy may also be measured in kilocalories (kcal) and kilojoules (kJ).This can create confusion, especially if you’re counting calories or comparing the calorie contents of various foods and drinks. This article explains what calories are and how they compare with kcal and kJ, as well as how to convert between the two. <figure><picture class="css-16pk1is"><source srcset="https://i0.wp.com/post.healthline.com/wp-content/uploads/2020/10/grocery-shopping-store-label-package-food-1296x728-header.jpg?w=1575 750w" media="(min-width: 1190px)"><source srcset="https://i0.wp.com/post.healthline.com/wp-content/uploads/2020/10/grocery-shopping-store-label-package-food-1296x728-header.jpg?w=1575 750w" media="(min-width: 990px)"><source srcset="https://i0.wp.com/post.healthline.com/wp-content/uploads/2020/10/grocery-shopping-store-label-package-food-1296x728-header.jpg?w=1845 879w" media="(min-width: 768px)"><img src="https://i0.wp.com/post.healthline.com/wp-content/uploads/2020/10/grocery-shopping-store-label-package-food-1296x728-header.jpg?w=1155&amp;h=1528" alt="Woman looking at the nutrition facts label of a product in a supermarket" width="690" height="388"></picture><figcaption dir="auto">Andresr/Getty Images</figcaption></figure><div><a name="differences">Main differences</a></div>When it comes to calories, they may be “small” or “large.” If the “c” in calories is uppercase, it indicates a large calorie, and if it’s lowercase, it indicates a small calorie.A large calorie estimates the amount of energy required to raise the temperature of 1 kg (2.2 pounds) of water by 1°C (34°F) (<hl-trusted-source source="PubMed Central" rationale="Highly respected database from the National Institutes of Health" dir="ltr"><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2238749/" rel="noopener noreferrer" dir="ltr">1</a></hl-trusted-source>).On the other hand, a small calorie estimates the amount of energy it takes to raise the temperature of 1 gram (0.035 ounces) of water by 1°C (34°F) (<hl-trusted-source source="PubMed Central" rationale="Highly respected database from the National Institutes of Health" dir="ltr"><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2238749/" rel="noopener noreferrer" dir="ltr">1</a></hl-trusted-source>).By these definitions, 1 large calorie equals 1,000 small calories, as 1 kg equals 1,000 grams.To avoid confusion between large and small calories, it’s thought that the term kilocalorie — the prefix “kilo” meaning 1,000 — was created to refer to a large calorie (<hl-trusted-source source="PubMed Central" rationale="Highly respected database from the National Institutes of Health" dir="ltr"><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2238749/" rel="noopener noreferrer" dir="ltr">1</a></hl-trusted-source>).However, the term small calorie is rarely used today outside of physics and chemistry research. Instead, the terms calories — capitalized or not — and kcal are used interchangeably and refer to the same amount of energy in relation to food or <a href="https://www.healthline.com/health/what-exercise-burns-the-most-calories" dir="ltr">energy burned with exercise</a>. Therefore, you don’t need to convert them, as 1 kilocalorie equals 1 calorie in nutrition. Calories may also be expressed as kilojoules (kJ). One calorie (kcal) equals 4.18 kJ or 4,184 joules (J) (<hl-trusted-source source="PubMed Central" rationale="Highly respected database from the National Institutes of Health" dir="ltr"><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2238749/" rel="noopener noreferrer" dir="ltr">1</a></hl-trusted-source>).To convert from calories to kJ, multiple calories by 4.18. Conversely, to convert from kJ to calories, divide kJ by 4.18. For example, a medium-sized banana (118 grams) provides 105 calories (kcal) or 439 kJ (<hl-trusted-source source="FoodData Central" rationale="Highly respected food and nutrition database from the United States Department of Agriculture,Governmental authority" dir="ltr"><a href="https://fdc.nal.usda.gov/fdc-app.html#/food-details/786652/nutrients" rel="noopener noreferrer" dir="ltr">2</a></hl-trusted-source>).<BLOCKQUOTE>SummaryWhen it comes to nutrition and exercise, kilocalories (kcal) and calories equal the same amount of energy. Calories may also be expressed as kilojoules (kJ), with one calorie or kcal equaling 4.18 kJ. </BLOCKQUOTE><div>HEALTHLINE RESOURCES</div><div>Take our free 3-question diet quiz</div>Our free assessment ranks the best diets for you based on your answers to 3 quick questions.<div><a name="uses">How are these terms used?</a></div>Regulations require that food and beverage manufacturers display a <a href="https://www.healthline.com/nutrition/new-nutrition-facts-label-2020" dir="ltr">nutrition facts label</a> on their products. It lists, among other information, the amount of energy the item contains per serving or weight (<hl-trusted-source source="PubMed Central" rationale="Highly respected database from the National Institutes of Health" dir="ltr"><a href="https://www.ncbi.nlm.nih.gov/books/NBK235562/" rel="noopener noreferrer" dir="ltr">3</a></hl-trusted-source>).The nutrition facts label serves to help inform you about the healthfulness of packaged foods and beverages, as well as whether they contain ingredients that you may need to avoid due to an allergy, intolerance, or personal preference.Depending on where you live, the nutrition facts panel may express the energy value of a food or beverage in calories, kcal, kJ, or a combination of them.Below is a list of countries and which label they use for energy (<hl-trusted-source source="Food and Drug Administration (FDA)" rationale="Governmental authority" dir="ltr"><a href="https://www.fda.gov/files/food/published/Food-Labeling-Guide-%28PDF%29.pdf" rel="noopener noreferrer" dir="ltr">4</a></hl-trusted-source><UL><LI>United States: Calories</LI><LI>Canada: Calories</LI><LI>European Union (EU): kJ and kcal</LI><LI>Australia and New Zealand: kJ or both kJ and kcal</LI><LI>China: kJ</LI></UL>Manufacturers determine the number of calories a food or beverage contains based on the amount of energy-supplying nutrients it contains. The three main energy-supplying nutrients are protein, carbs, and fats.Protein and carbs each provide about 4 calories (16.7 kJ) per gram, while fat provides 9 calories per gram (37.6 kJ) (<hl-trusted-source source="PubMed Central" rationale="Highly respected database from the National Institutes of Health" dir="ltr"><a href="https://www.ncbi.nlm.nih.gov/books/NBK218769/" rel="noopener noreferrer" dir="ltr">9</a></hl-trusted-source>).<a href="https://www.healthline.com/nutrition/alcohol-good-or-bad" dir="ltr">Alcohol</a> also supplies 7 calories (29.3 kJ) per gram.Manufacturers round to the nearest 1-gram increment, so if you were to quantify the number of calories or kJ from each of the macronutrients, they may add up to be slightly different than the number listed on the nutrition label (<hl-trusted-source source="Food and Drug Administration (FDA)" rationale="Governmental authority" dir="ltr"><a href="https://www.fda.gov/files/food/published/Food-Labeling-Guide-%28PDF%29.pdf" rel="noopener noreferrer" dir="ltr">4</a></hl-trusted-source>).Moreover, the nutrition labels of foods that contain fiber, which is classified as a carbohydrate, may contain fewer calories than what you calculate. This is because fiber, <a href="https://www.healthline.com/nutrition/different-types-of-fiber" dir="ltr">depending on the type</a>, is either indigestible or poorly digested, thus contributing zero or few calories (<hl-trusted-source source="Food and Drug Administration (FDA)" rationale="Governmental authority" dir="ltr"><a href="https://www.fda.gov/media/113663/download" rel="noopener noreferrer" dir="ltr">10</a></hl-trusted-source>).<BLOCKQUOTE>SummaryMost packaged foods and beverages contain a nutrition label that lists the amount of energy the item contains in calories, kcal, kJ, or some combination of these. </BLOCKQUOTE><div><a name="bottom-line">The bottom line</a></div><a href="https://www.healthline.com/nutrition/how-many-calories-per-day" dir="ltr">Calories</a> are a measure of energy in nutrition and exercise. Calories and kcal are used interchangeably and refer to the same amount of energy. Calories or kcal may also be measured in kJ, with one calorie (kcal) equaling 4.18 kJ. <div>ADVERTISEMENT</div><div>Start a custom weight loss program</div>Noom helps you adopt healthy habits so you can lose weight and keep it off. Your program is customized to your goals and fitness needs. Just take a quick assessment and get started today.

Calories refer to the amount of energy in foods or drinks or the amount of energy you burn exercising, but you may be confused by seeing different units used to describe them. This article explains what calories are and how they compare with kcal and kJ.

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Food

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Health

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Exercise & Fitness

Calories are a measure of energy. They refer to the amount of energy in foods and beverages, or the amount of energy you burn exercising.

Depending on where you live, energy may also be measured in kilocalories (kcal) and kilojoules (kJ).

This can create confusion, especially if you’re counting calories or comparing the calorie contents of various foods and drinks.

This article explains what calories are and how they compare with kcal and kJ, as well as how to convert between the two.

When it comes to calories, they may be “small” or “large.”

If the “c” in calories is uppercase, it indicates a large calorie, and if it’s lowercase, it indicates a small calorie.

A large calorie estimates the amount of energy required to raise the temperature of 1 kg (2.2 pounds) of water by 1°C (34°F) (<hl-trusted-source dir="ltr" rationale="Highly respected database from the National Institutes of Health" source="PubMed Central"><a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2238749/" rel="noopener noreferrer">1 </a> </hl-trusted-source>

On the other hand, a small calorie estimates the amount of energy it takes to raise the temperature of 1 gram (0.035 ounces) of water by 1°C (34°F) (<hl-trusted-source dir="ltr" rationale="Highly respected database from the National Institutes of Health" source="PubMed Central"><a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2238749/" rel="noopener noreferrer">1 </a> </hl-trusted-source>

By these definitions, 1 large calorie equals 1,000 small calories, as 1 kg equals 1,000 grams.

To avoid confusion between large and small calories, it’s thought that the term kilocalorie — the prefix “kilo” meaning 1,000 — was created to refer to a large calorie (<hl-trusted-source dir="ltr" rationale="Highly respected database from the National Institutes of Health" source="PubMed Central"><a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2238749/" rel="noopener noreferrer">1 </a> </hl-trusted-source>

However, the term small calorie is rarely used today outside of physics and chemistry research.

Instead, the terms calories — capitalized or not — and kcal are used interchangeably and refer to the same amount of energy in relation to food or <a dir="ltr" href="https://www.healthline.com/health/what-exercise-burns-the-most-calories">energy burned with exercise </a>.

Therefore, you don’t need to convert them, as 1 kilocalorie equals 1 calorie in nutrition.

Calories may also be expressed as kilojoules (kJ).

One calorie (kcal) equals 4.18 kJ or 4,184 joules (J) (<hl-trusted-source dir="ltr" rationale="Highly respected database from the National Institutes of Health" source="PubMed Central"><a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2238749/" rel="noopener noreferrer">1 </a> </hl-trusted-source>

To convert from calories to kJ, multiple calories by 4.18. Conversely, to convert from kJ to calories, divide kJ by 4.18.

For example, a medium-sized banana (118 grams) provides 105 calories (kcal) or 439 kJ (<hl-trusted-source dir="ltr" rationale="Highly respected food and nutrition database from the United States Department of Agriculture,Governmental authority" source="FoodData Central"><a dir="ltr" href="https://fdc.nal.usda.gov/fdc-app.html#/food-details/786652/nutrients" rel="noopener noreferrer">2 </a> </hl-trusted-source>

When it comes to nutrition and exercise, kilocalories (kcal) and calories equal the same amount of energy. Calories may also be expressed as kilojoules (kJ), with one calorie or kcal equaling 4.18 kJ.

Our free assessment ranks the best diets for you based on your answers to 3 quick questions.

Regulations require that food and beverage manufacturers display a <a dir="ltr" href="https://www.healthline.com/nutrition/new-nutrition-facts-label-2020">nutrition facts label </a>on their products. It lists, among other information, the amount of energy the item contains per serving or weight (<hl-trusted-source dir="ltr" rationale="Highly respected database from the National Institutes of Health" source="PubMed Central"><a dir="ltr" href="https://www.ncbi.nlm.nih.gov/books/NBK235562/" rel="noopener noreferrer">3 </a> </hl-trusted-source>

The nutrition facts label serves to help inform you about the healthfulness of packaged foods and beverages, as well as whether they contain ingredients that you may need to avoid due to an allergy, intolerance, or personal preference.

Depending on where you live, the nutrition facts panel may express the energy value of a food or beverage in calories, kcal, kJ, or a combination of them.

Below is a list of countries and which label they use for energy (<hl-trusted-source dir="ltr" rationale="Governmental authority" source="Food and Drug Administration (FDA)"><a dir="ltr" href="https://www.fda.gov/files/food/published/Food-Labeling-Guide-%28PDF%29.pdf" rel="noopener noreferrer">4 </a> </hl-trusted-source>

<ul><li>United States: Calories </li><li>Canada: Calories </li><li>European Union (EU): kJ and kcal </li><li>Australia and New Zealand: kJ or both kJ and kcal </li><li>China: kJ </li> </ul>

Manufacturers determine the number of calories a food or beverage contains based on the amount of energy-supplying nutrients it contains.

The three main energy-supplying nutrients are protein, carbs, and fats.

Protein and carbs each provide about 4 calories (16.7 kJ) per gram, while fat provides 9 calories per gram (37.6 kJ) (<hl-trusted-source dir="ltr" rationale="Highly respected database from the National Institutes of Health" source="PubMed Central"><a dir="ltr" href="https://www.ncbi.nlm.nih.gov/books/NBK218769/" rel="noopener noreferrer">9 </a> </hl-trusted-source>

<a dir="ltr" href="https://www.healthline.com/nutrition/alcohol-good-or-bad">Alcohol </a>also supplies 7 calories (29.3 kJ) per gram.

Manufacturers round to the nearest 1-gram increment, so if you were to quantify the number of calories or kJ from each of the macronutrients, they may add up to be slightly different than the number listed on the nutrition label (<hl-trusted-source dir="ltr" rationale="Governmental authority" source="Food and Drug Administration (FDA)"><a dir="ltr" href="https://www.fda.gov/files/food/published/Food-Labeling-Guide-%28PDF%29.pdf" rel="noopener noreferrer">4 </a> </hl-trusted-source>

Moreover, the nutrition labels of foods that contain fiber, which is classified as a carbohydrate, may contain fewer calories than what you calculate.

This is because fiber, <a dir="ltr" href="https://www.healthline.com/nutrition/different-types-of-fiber">depending on the type </a>, is either indigestible or poorly digested, thus contributing zero or few calories (<hl-trusted-source dir="ltr" rationale="Governmental authority" source="Food and Drug Administration (FDA)"><a dir="ltr" href="https://www.fda.gov/media/113663/download" rel="noopener noreferrer">10 </a> </hl-trusted-source>

Most packaged foods and beverages contain a nutrition label that lists the amount of energy the item contains in calories, kcal, kJ, or some combination of these.

<a dir="ltr" href="https://www.healthline.com/nutrition/how-many-calories-per-day">Calories </a>are a measure of energy in nutrition and exercise.

Calories and kcal are used interchangeably and refer to the same amount of energy.

Calories or kcal may also be measured in kJ, with one calorie (kcal) equaling 4.18 kJ.

Noom helps you adopt healthy habits so you can lose weight and keep it off. Your program is customized to your goals and fitness needs. Just take a quick assessment and get started today.

Kcal vs. Calories: Differences and How to Convert

Calories are a measure of energy

Small and large calories

1 kilocalorie = 1 calorie in nutrition

To convert from calories to kJ

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