Kilojoules to Calories (kJ to kcal): Formula & Chart

Converting kilojoules to calories is useful when reading nutrition labels, comparing food energy values, tracking dietary energy, understanding exercise measurements, or performing scientific calculations.

Kilojoules (kJ) and calories are both units of energy. However, the word “calorie” can refer to two different quantities: the small calorie (cal) and the kilocalorie (kcal), commonly called a food Calorie.

This distinction is important because:

1 kilocalorie (kcal) = 1,000 small calories (cal)

For food energy, the most useful conversion is:

1 kilojoule (kJ) ≈ 0.239006 kilocalories (kcal)

For small calories:

1 kilojoule (kJ) ≈ 239.006 calories (cal)

In this guide, you’ll learn how to convert kilojoules to calories, understand the difference between calories and kilocalories, explore detailed conversion charts, and discover practical applications in nutrition, exercise, and science.

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How Many Calories Are in One Kilojoule?

The answer depends on which type of calorie you mean.

Kilojoules to Food Calories (kcal)

One kilojoule equals approximately 0.239006 kilocalories.

1 kJ ≈ 0.239006 kcal

In nutrition, one kilocalorie is commonly written as one Calorie with a capital C.

Therefore:

1 kJ ≈ 0.239006 food Calories

Kilojoules to Small Calories (cal)

One kilojoule equals approximately 239.006 small calories.

1 kJ ≈ 239.006 cal

This relationship uses the thermochemical calorie, defined as exactly 4.184 joules.

Common Kilojoules to Food Calories Conversions

1 kJ ≈ 0.24 kcal
10 kJ ≈ 2.39 kcal
50 kJ ≈ 11.95 kcal
100 kJ ≈ 23.90 kcal
200 kJ ≈ 47.80 kcal
500 kJ ≈ 119.50 kcal
1,000 kJ ≈ 239.01 kcal
2,000 kJ ≈ 478.01 kcal

For everyday nutrition calculations, divide kilojoules by approximately 4.184.

What Is the Kilojoules to Calories Formula?

The conversion formula depends on whether you need kilocalories or small calories.

Formula 1: Kilojoules to Kilocalories

To convert kilojoules into food Calories:

Kilocalories = Kilojoules ÷ 4.184

Or:

kcal = kJ × 0.239005736

This formula is appropriate for most food and nutrition calculations.

Formula 2: Kilojoules to Small Calories

To convert kilojoules into small thermochemical calories:

Calories (cal) = Kilojoules × 239.005736

For example, 5 kJ equals approximately 1,195.03 small calories.

Why Are There Two Formulas?

The small calorie and the kilocalorie differ by a factor of 1,000.

One kilocalorie contains 1,000 small calories.

For this reason, a food label displaying 200 Calories generally means 200 kilocalories, not 200 small calories.

Step-by-Step Kilojoules to Calories Examples

Example 1: Convert 100 kJ to Calories

100 ÷ 4.184 ≈ 23.9006

Result: 100 kJ ≈ 23.90 kcal

Example 2: Convert 250 kJ to Calories

250 ÷ 4.184 ≈ 59.7514

Result: 250 kJ ≈ 59.75 kcal

Example 3: Convert 500 kJ to Calories

500 ÷ 4.184 ≈ 119.5029

Result: 500 kJ ≈ 119.50 kcal

Example 4: Convert 1,000 kJ to Calories

1,000 ÷ 4.184 ≈ 239.0057

Result: 1,000 kJ ≈ 239.01 kcal

Example 5: Convert 2,000 kJ to Calories

2,000 ÷ 4.184 ≈ 478.0115

Result: 2,000 kJ ≈ 478.01 kcal

Example 6: Convert 5,000 kJ to Calories

5,000 ÷ 4.184 ≈ 1,195.0287

Result: 5,000 kJ ≈ 1,195.03 kcal

Kilojoules to Calories Conversion Chart

The following table shows kilojoules converted into kilocalories (food Calories) and small thermochemical calories.

Kilojoules (kJ)	Food Calories (kcal)	Small Calories (cal)
1 kJ	0.24 kcal	239.01 cal
5 kJ	1.20 kcal	1,195.03 cal
10 kJ	2.39 kcal	2,390.06 cal
20 kJ	4.78 kcal	4,780.11 cal
50 kJ	11.95 kcal	11,950.29 cal
100 kJ	23.90 kcal	23,900.57 cal
150 kJ	35.85 kcal	35,850.86 cal
200 kJ	47.80 kcal	47,801.15 cal
250 kJ	59.75 kcal	59,751.43 cal
300 kJ	71.70 kcal	71,701.72 cal
400 kJ	95.60 kcal	95,602.29 cal
500 kJ	119.50 kcal	119,502.87 cal
600 kJ	143.40 kcal	143,403.44 cal
750 kJ	179.25 kcal	179,254.30 cal
800 kJ	191.20 kcal	191,204.59 cal
1,000 kJ	239.01 kcal	239,005.74 cal
1,200 kJ	286.81 kcal	286,806.88 cal
1,500 kJ	358.51 kcal	358,508.60 cal
2,000 kJ	478.01 kcal	478,011.47 cal
2,500 kJ	597.51 kcal	597,514.34 cal
3,000 kJ	717.02 kcal	717,017.21 cal
4,000 kJ	956.02 kcal	956,022.94 cal
5,000 kJ	1,195.03 kcal	1,195,028.68 cal
8,000 kJ	1,912.05 kcal	1,912,045.89 cal
10,000 kJ	2,390.06 kcal	2,390,057.36 cal

Values are rounded to two decimal places. Calculations use the thermochemical calorie.

For additional energy conversions, use the Multiconverts Energy Converter.

Convert Kilojoules to Calories Online

An online energy converter helps you calculate equivalent energy values without performing manual calculations.

The Multiconverts Energy Converter helps you convert between kilojoules, joules, kilocalories, calories, kilowatt-hours, and other supported energy units.

How to Use the Energy Converter

Open the Multiconverts Energy Converter.
Select kilojoules (kJ) as the starting unit.
Choose kilocalories (kcal) for food Calories or calories (cal) for small calories.
Enter the energy value you want to convert.
View the converted result.

For example, entering 840 kJ and selecting kilocalories produces approximately 200.76 kcal.

Always select the correct calorie unit to avoid a thousandfold difference.

What Is a Kilojoule?

A kilojoule is a metric unit of energy equal to 1,000 joules.

1 kJ = 1,000 J

The joule is the SI unit of energy.

Kilojoules are commonly used for:

Food energy labels
Nutrition information
Scientific experiments
Chemistry
Physics
Exercise energy measurements
Thermal energy calculations

Kilojoules are especially common on food packaging in countries such as Australia and New Zealand.

What Is a Calorie?

A calorie is a unit of energy.

However, the word calorie can refer to different quantities.

Small Calorie (cal)

The small calorie is a traditional energy unit.

For the thermochemical calorie:

1 cal = 4.184 J

Small calories are sometimes used in scientific contexts.

Kilocalorie (kcal)

One kilocalorie equals 1,000 small calories.

1 kcal = 1,000 cal

Therefore:

1 kcal = 4,184 J

In nutrition, one kilocalorie is commonly called one Calorie.

For example, a food product labeled as containing 150 Calories generally provides approximately 150 kcal of food energy.

Kilojoules vs Calories: What Is the Difference?

Kilojoules and calories both measure energy, but they belong to different measurement conventions.

Characteristic	Kilojoule	Kilocalorie
Symbol	kJ	kcal
Measurement	Energy	Energy
Unit system	Metric, based on SI	Traditional energy unit
Joule equivalent	1,000 J	4,184 J
Common use	Food labels and science	Nutrition and food energy
Conversion	1 kJ ≈ 0.239 kcal	1 kcal = 4.184 kJ

A kilocalorie represents more energy than a kilojoule.

That is why a food product may display a larger number in kilojoules than in kilocalories.

When Do You Need to Convert Kilojoules to Calories?

1. Reading Nutrition Labels

Food packaging may display energy values in kilojoules.

Suppose a product contains 850 kJ per serving.

Convert the value:

850 ÷ 4.184 ≈ 203.1549

850 kJ ≈ 203.15 kcal

This conversion helps when comparing nutrition labels that use different units.

2. Comparing Food Products

Two food products may report their energy values using different measurement units.

Suppose one product provides 600 kJ and another provides 150 kcal.

Convert the first product:

600 ÷ 4.184 ≈ 143.40 kcal

The first product provides approximately 143.40 kcal, while the second provides 150 kcal.

This comparison considers energy only, not the products’ overall nutritional value.

3. Understanding Exercise Energy

Fitness equipment and activity trackers may display estimated energy expenditure in kilojoules or kilocalories.

Suppose a device estimates 1,200 kJ of energy expenditure.

1,200 ÷ 4.184 ≈ 286.8069

1,200 kJ ≈ 286.81 kcal

This is a unit conversion of the device’s estimate. It does not establish that the estimate is physiologically exact.

4. Scientific Calculations

Scientific experiments may report energy in joules or kilojoules.

Suppose a process releases 50 kJ of energy.

50 ÷ 4.184 ≈ 11.9503

50 kJ ≈ 11.95 kcal

Alternatively, in small calories:

50 × 239.005736 ≈ 11,950.29 cal

The appropriate unit depends on the scientific context.

5. Understanding Daily Food Energy

Nutrition references may describe daily food energy in kilojoules or kilocalories.

For example, 8,400 kJ corresponds to:

8,400 ÷ 4.184 ≈ 2,007.65

8,400 kJ ≈ 2,007.65 kcal

This is an energy equivalence, not a personalized dietary recommendation.

Individual energy needs vary according to many factors.

6. International Food Packaging

Food labels may display energy in different units depending on the country.

A product might list:

Energy: 1,050 kJ

Convert to kilocalories:

1,050 ÷ 4.184 ≈ 250.9560

1,050 kJ ≈ 250.96 kcal

This helps consumers interpret international product information.

Common Food Energy Conversions

The following chart provides quick reference values for kilojoules and food Calories.

Kilojoules	Food Calories
100 kJ	23.90 kcal
200 kJ	47.80 kcal
300 kJ	71.70 kcal
400 kJ	95.60 kcal
500 kJ	119.50 kcal
600 kJ	143.40 kcal
700 kJ	167.30 kcal
800 kJ	191.20 kcal
900 kJ	215.11 kcal
1,000 kJ	239.01 kcal
1,200 kJ	286.81 kcal
1,500 kJ	358.51 kcal
2,000 kJ	478.01 kcal
2,500 kJ	597.51 kcal
3,000 kJ	717.02 kcal

These values represent equivalent energy amounts.

They do not indicate whether a particular food or meal is nutritionally appropriate.

How to Convert Calories to Kilojoules

Sometimes you need to reverse the conversion.

To convert kilocalories into kilojoules, multiply by 4.184.

Kilojoules = Kilocalories × 4.184

Example 1: Convert 100 kcal to kJ

100 × 4.184 = 418.4

Result: 100 kcal = 418.4 kJ

Example 2: Convert 200 kcal to kJ

200 × 4.184 = 836.8

Result: 200 kcal = 836.8 kJ

Example 3: Convert 500 kcal to kJ

500 × 4.184 = 2,092

Result: 500 kcal = 2,092 kJ

Example 4: Convert 1,000 kcal to kJ

1,000 × 4.184 = 4,184

Result: 1,000 kcal = 4,184 kJ

For small thermochemical calories, multiply by 0.004184 instead.

Kilojoules vs Joules vs Calories vs Kilowatt-Hours

Different energy units are useful in different contexts.

Unit	Equivalent Energy
1 J	1 joule
1 kJ	1,000 J
1 cal	4.184 J
1 kcal	4,184 J
1 kJ	Approximately 0.239006 kcal
1 kWh	3,600 kJ
1 kWh	Approximately 860.42 kcal

Kilojoules and kilocalories are commonly used in nutrition.

Kilowatt-hours are frequently used for electrical energy consumption.

Are Calories and Kilocalories the Same?

In everyday nutrition, the words “Calories” and “kilocalories” are often used to describe the same quantity.

However, in scientific terminology:

1 kcal = 1,000 cal

The capitalization matters in conventional nutrition notation:

cal = small calorie
kcal = kilocalorie
Cal = food Calorie, equivalent to one kilocalorie

This distinction helps prevent errors when converting energy units.

How to Estimate Kilojoules to Calories Without a Calculator

For quick mental calculations, divide kilojoules by approximately 4.2.

For example:

420 kJ ÷ 4.2 = 100 kcal

The more precise calculation is:

420 ÷ 4.184 ≈ 100.38 kcal

Another useful shortcut is to multiply kilojoules by 0.24.

For example:

500 kJ × 0.24 = 120 kcal

The precise result is approximately 119.50 kcal.

These approximations are useful for everyday comparisons.

For scientific or technical calculations, use the exact conversion relationship.

Common Mistakes When Converting Kilojoules to Calories

Confusing Calories With Small Calories

One food Calorie equals 1,000 small calories.

Always verify whether the intended unit is kcal or cal.

Using the Wrong Conversion Factor

To convert kJ into kcal, divide by 4.184.

To convert kcal into kJ, multiply by 4.184.

Confusing Energy With Power

Kilojoules measure energy.

Kilowatts measure power.

They are related but represent different physical quantities.

Rounding Too Early

For scientific calculations, keep sufficient precision until the final result.

Assuming All Nutrition Labels Use the Same Units

Some countries emphasize kilojoules, while others commonly display kilocalories.

Always check the unit printed on the label.

Treating Energy Conversion as Nutritional Advice

A unit conversion does not determine a person’s dietary needs or the nutritional quality of food.

Frequently Asked Questions About Kilojoules to Calories

How many Calories are in one kilojoule?

One kilojoule equals approximately 0.239006 food Calories, or kilocalories.

How many small calories are in one kilojoule?

One kilojoule equals approximately 239.006 thermochemical calories.

What is the formula for kJ to kcal?

Divide kilojoules by 4.184.

How many Calories are in 100 kJ?

100 kJ equals approximately 23.90 kcal.

How many Calories are in 200 kJ?

200 kJ equals approximately 47.80 kcal.

How many Calories are in 250 kJ?

250 kJ equals approximately 59.75 kcal.

How many Calories are in 500 kJ?

500 kJ equals approximately 119.50 kcal.

How many Calories are in 750 kJ?

750 kJ equals approximately 179.25 kcal.

How many Calories are in 800 kJ?

800 kJ equals approximately 191.20 kcal.

How many Calories are in 1,000 kJ?

1,000 kJ equals approximately 239.01 kcal.

How many Calories are in 1,200 kJ?

1,200 kJ equals approximately 286.81 kcal.

How many Calories are in 1,500 kJ?

1,500 kJ equals approximately 358.51 kcal.

How many Calories are in 2,000 kJ?

2,000 kJ equals approximately 478.01 kcal.

How many Calories are in 2,500 kJ?

2,500 kJ equals approximately 597.51 kcal.

How many Calories are in 3,000 kJ?

3,000 kJ equals approximately 717.02 kcal.

How many Calories are in 5,000 kJ?

5,000 kJ equals approximately 1,195.03 kcal.

How many Calories are in 8,000 kJ?

8,000 kJ equals approximately 1,912.05 kcal.

How many kilojoules are in one kilocalorie?

One kilocalorie equals exactly 4.184 kilojoules.

Is a food Calorie the same as a kilocalorie?

Yes. In conventional nutrition terminology, one food Calorie equals one kilocalorie.

How do I convert calories to kilojoules?

For food Calories, multiply kilocalories by 4.184.

Can I convert kilojoules to calories online?

Yes. Use an online energy converter to calculate equivalent energy values quickly.

Conclusion

Converting kilojoules to calories is useful for understanding food labels, comparing nutritional information, interpreting exercise measurements, and performing scientific energy calculations.

The essential conversion formula for food Calories is: