Kilocalories to Kilojoules

1 kcal = 4.184 kJ

Nutrition labels in the United States list food energy in Calories, which are kilocalories, while Australia, New Zealand, and many scientific papers use kilojoules. Converting kcal to kJ helps dietitians, athletes, and travelers compare labels and meet reporting requirements in SI units.

From

When you need to convert kilocalories to kilojoules

Comparing a US nutrition label with an Australian product in kJ
Reporting dietary energy intake in SI units for research
Setting daily energy targets in a fitness app that uses kilojoules
Converting exercise energy expenditure for a sports science report

How to convert kilocalories to kilojoules

kJ = kcal × 4.184

Example: 5 kcal = 20.92 kJ

Common food energy values

Kilocalories (kcal)	Kilojoules (kJ)
100 kcal	418.4 kJ
200 kcal	836.8 kJ
250 kcal	1,046 kJ
500 kcal	2,092 kJ
1,000 kcal	4,184 kJ
1,500 kcal	6,276 kJ
2,000 kcal	8,368 kJ
2,500 kcal	10,460 kJ

Tips for converting kilocalories to kilojoules

One kilocalorie is defined as 4.184 kJ (thermochemical). Multiplying by about 4.2 is a quick estimate within 1%.
A food Calorie with a capital C is a kilocalorie, not a small calorie, so do not multiply by an extra 1,000.
Energy numbers in kJ look about four times larger, which can make a familiar food seem higher in energy at first glance.

Kilocalories to Kilojoules conversion table

Kilocalories (kcal)	Kilojoules (kJ)
1 kcal	4.184 kJ
2 kcal	8.368 kJ
3 kcal	12.552 kJ
4 kcal	16.736 kJ
5 kcal	20.92 kJ
6 kcal	25.104 kJ
7 kcal	29.288 kJ
8 kcal	33.472 kJ
9 kcal	37.656 kJ
10 kcal	41.84 kJ
15 kcal	62.76 kJ
20 kcal	83.68 kJ
25 kcal	104.6 kJ
30 kcal	125.52 kJ
40 kcal	167.36 kJ
50 kcal	209.2 kJ
75 kcal	313.8 kJ
100 kcal	418.4 kJ
250 kcal	1,046 kJ
500 kcal	2,092 kJ
1,000 kcal	4,184 kJ

About the units

Kilocalories: The kilocalorie, written "Calorie" on food labels, is the energy needed to heat 1 kg of water by 1 °C. This converter uses the thermochemical value of 4,184 joules.

Kilojoules: The kilojoule equals 1,000 joules. Food labels in Australia, the EU and other regions list energy in kJ.

Frequently asked questions

How many kilojoules are in 1 kilocalorie?

1 kilocalorie equals 4.184 kilojoules.

How many kilocalories are in 1 kilojoule?

1 kilojoule equals 0.2390057 kilocalories.

How do I convert kilocalories to kilojoules?

Use the formula kJ = kcal × 4.184.

What is 10 kilocalories in kilojoules?

10 kilocalories equals 41.84 kilojoules.

Related conversions

Factors: NIST SP 811 · SI Brochure · NIST Handbook 44 — Updated October 17, 2026