calories to kj | Exact Decimal + Formula

1 Calorie = 0.004184 Kilojoule

One kilojoule equals about 239 calories (exactly 239.0057361 cal). Real-world use: chemistry, nutrition science, and physical-activity calculations. This page expresses those values in kilojoules, which is used for food-energy labels in many countries and technical energy measurements. Enter any value above — the result updates instantly, and a 1–1000 reference table follows below.

About Calorie and Kilojoule

Calorie (cal)

A (small) calorie is the energy needed to raise one gram of water by one degree Celsius, exactly 4.184 joules.

Where it's used: Chemistry, nutrition science, and physical-activity calculations.

Kilojoule (kJ)

A kilojoule is 1,000 joules.

Where it's used: Food-energy labels in many countries and technical energy measurements.

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Precision

Formula

kJ = cal × 0.004184

To convert Calorie to Kilojoule, use the formula displayed above.

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Calorie to Kilojoule: Quick Reference Table

Calorie	Kilojoule (Decimal)	Fraction	Real-world equivalent
0.001 cal	0.000004 kJ	-	fractional unit measurement
0.01 cal	0.000042 kJ	-	fractional unit measurement
0.1 cal	0.000418 kJ	-	fractional unit measurement
0.5 cal	0.002092 kJ	-	fractional unit measurement
1 cal	0.004184 kJ	-	fractional unit measurement
2 cal	0.008368 kJ	-	fractional unit measurement
5 cal	0.02092 kJ	-	fractional unit measurement
10 cal	0.04184 kJ	-	fractional unit measurement
25 cal	0.1046 kJ	-	fractional unit measurement
50 cal	0.2092 kJ	-	fractional unit measurement
100 cal	0.4184 kJ	-	fractional unit measurement
250 cal	1.046 kJ	-	standard single unit scale
500 cal	2.092 kJ	-	standard single unit scale
1000 cal	4.184 kJ	-	standard single unit scale

cal to kJ Formula and Examples

Direct Formula kJ = cal × 0.004184

Inverse Formula cal = kJ × 239.005736

Mental Math Shortcut

Divide the value by roughly 239 to quickly estimate the converted result.

Common Calorie to Kilojoule Calculations

5 cal = 0.02092 kJ
10 cal = 0.04184 kJ
50 cal = 0.2092 kJ
100 cal = 0.4184 kJ
500 cal = 2.092 kJ

Precision & Practical Use

For example, 10 cal = 0.04184 kJ — roughly fractional unit measurement.

Utility bills and appliance ratings are given in whole kWh or BTU. Round converted figures to match the source document you're comparing against.

How to Convert Calorie to Kilojoule

How many kilojoules are in one calorie?

One Calorie (cal) equals 0.004184 Kilojoule (kJ). To convert calories to kilojoules, multiply the calorie value by 0.004184.

How do I convert Calorie to Kilojoule?

Multiply your calorie value by 0.004184 to get the result in Kilojoule: kJ = cal × 0.004184. For example, 5 cal = 0.02092 kJ.

What is the formula for converting cal to kJ?

The conversion formula is kJ = cal × 0.004184. Use the calculator above for any value, and see the reference table below for common inputs from 0.001 to 1000.

Is there a quick mental estimate for cal to kJ?