Calories to Kilojoules

Kilocalories (food Calories) (kcal) to kilojoules (kJ).

Value

Convert to

8,368kJ

Precision (significant figures)

Formula

kJ = kcal × 4.184

1 kcal = 4.184 kJ

kJ = kcal × 4.184 exactly, using the thermochemical calorie. A food Calorie (capital C) is one kilocalorie, so a 250 kcal snack is 1,046 kJ and a 2,000 kcal daily diet is 8,368 kJ. Labels in Australia and the EU show kilojoules first.

Formula

Worked example

Start with 2,000 kcal.
Multiply by 4.184 (kJ per kcal): 2,000 × 4.184 = 8,368 kJ.

Calories to kj chart

Kilocalories (food Calories) (kcal)	Kilojoules (kJ)
1	4.184
50	209.2
100	418.4
150	627.6
200	836.8
250	1,046
300	1,255.2
400	1,673.6
500	2,092
800	3,347.2
1,000	4,184
1,500	6,276
1,800	7,531.2
2,000	8,368
2,500	10,460
3,000	12,552

When you need this conversion

Reading nutrition labels in Australia, New Zealand and the EU, tracking food in apps that use a different unit, and exercise or nutrition science.

Quick reference

1 kcal = 4.184 kJ
100 kcal = 418.4 kJ
250 kcal = 1,046 kJ
500 kcal = 2,092 kJ
2,000 kcal = 8,368 kJ
2,500 kcal = 10,460 kJ

Rule of thumb

Multiply by 4, then add 5%: 300 kcal gives 1,200 + 60 = 1,260 kJ (exact: 1,255.2).

Common mistakes

Mixing calorie sizes. A label reading “Energy 1,046 kJ / 250 kcal” is consistent. A figure of 250 cal usually means 250 kcal in everyday use, but in science it would be 1/1000 of that.

Using the International Table calorie. Engineering tables sometimes use 4.1868 J per calorie. Food labeling uses 4.184.

For the reverse, use kJ to kcal.

Questions

How many kJ is 1 kcal?

4.184 kJ.

How many kJ is 2,000 Calories?

8,368 kJ.

Is a Calorie the same as a kcal?

Yes. Food Calories with a capital C are kilocalories. A small calorie (cal) is 1/1000 of that.

Why do some labels use 4.2?

The EU and Australia round to 4.2 on some labels; the defined thermochemical factor is 4.184.

Sources

Last reviewed 2026-09-24. How we check values · Report a problem with this page