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Kilojoules to kilocalories

Multiply kilojoules by 0.239006 to get kilocalories.

1 kJ = 0.239006 kcalNIST SP 811
kJ
239.0057kcal

1,000 kJ = 239.0057 kcal

How to convert kilojoules to kilocalories

The kilocalorie is one thousand thermochemical calories (4184 J) — the "Calorie" on food labels. The kilojoule is one thousand joules — the metric food-energy unit used outside the US.

Worked example — 1,000 kJ: 1,000 × 0.239006 = 239.0057 kcal.

Kilojoules to kilocalories table

Common conversions. The reverse table is on kilocalories to kilojoules.
KilojoulesKilocalories
1 kJ0.239006 kcal
100 kJ23.9006 kcal
250 kJ59.7514 kcal
500 kJ119.5029 kcal
1,000 kJ239.0057 kcal
2,000 kJ478.0115 kcal
4,000 kJ956.0229 kcal
8,000 kJ1,912.0459 kcal
8,400 kJ2,007.6482 kcal

Reverse and related

About kilojoules and kilocalories

Kilojoule (kJ)

1 kJ = 0.239006 kcal

Definition. One thousand joules — the metric food-energy unit used outside the US

History and origin

The kilojoule is one thousand joules, the metric unit of energy built on the SI joule. It is the food-energy unit preferred where the metric system is standard.

Current use

Kilojoules are used on nutrition labels outside the United States and throughout physics and engineering.

Source: NIST SP 811, Appendix B; ISO 80000-5 (energy)

Kilocalorie (kcal)

1 kcal = 4.184 kJ

Definition. One thousand thermochemical calories (4184 J) — the "Calorie" on food labels

History and origin

The kilocalorie is one thousand calories, where the calorie was defined as the heat needed to warm one gram of water by one degree Celsius. On food labels the capitalised Calorie is really a kilocalorie.

Current use

Kilocalories, shown as Calories, measure food energy on US and many other nutrition labels.

Source: NIST SP 811, Appendix B; ISO 80000-5 (energy)

Where people use this

Kilojoules: nutrition labels outside the US, physics. Kilocalories: nutrition and diet, food labels. An 8400 kJ daily intake is about 2008 kcal.

How we know this is right
The factor is fixed by the standards that define the units, not chosen — so it is exact, not a measurement:
1 kcal = 4.184 kJ, so 1 kJ = 1 ÷ 4.184 = 0.239006 kcal.

Every value is carried to full double precision; the display is rounded.

Both units are defined in NIST SP 811, Appendix B; ISO 80000-5 (energy).

Questions people ask

How many kcal is 8400 kJ?

An 8400 kJ daily intake is about 2008 kcal. To convert kJ to kcal, divide by 4.184.

How many Calories in a kJ?

One kilojoule is about 0.239 food Calories (kcal).

How many kcal is 1000 kJ?

1000 kJ is about 239 kcal.

How do you convert kJ to Calories?

Divide the kilojoules by 4.184 to get food Calories, so a 500 kJ snack is about 120 kcal.

All kilojoule conversions