# Kilojoules to kilocalories converter

> Convert kilojoules to kilocalories (kJ to kcal) with the exact factor, a conversion chart and worked steps.

Interactive version: https://www.calcopenly.com/conversion/kj-to-kcal
Subject: Unit converters

Kilojoules on a food label may need conversion to the kilocalorie scale used in a diary. The arithmetic changes the energy unit, not the portion size. A daily total requires summing the energy for the portions actually recorded.

One kilojoule is about 0.2390057361 kilocalories, so 8700 kJ is 2,079.349904 kcal. To convert kJ to kcal, multiply by 0.2390057361; to convert back, multiply by 4.184.

The kilocalorie used on food labels is the thermochemical kilocalorie, exactly 4.184 kJ. The factor has no exact decimal form, so results are computed with 50 significant digits and rounded only for display.

## Inputs

- **Kilojoules (kJ)**

## Results

- Kilocalories (kcal) — main result
- Conversion
- 1 kcal in kilojoules (kJ)

## Formula

$$
\text{kilocalories} = \text{kilojoules} \times 0.239005736138
$$

## Worked examples

### 8700 kJ to kcal

- Kilojoules (kJ): 8700 kJ
- **Kilocalories: 2,079.3499044 kcal**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 1000 kJ to kcal

- Kilojoules (kJ): 1000 kJ
- **Kilocalories: 239.005736138 kcal**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 100 kJ to kcal

- Kilojoules (kJ): 100 kJ
- **Kilocalories: 23.9005736138 kcal**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

## Questions

### When would I convert kJ to kcal?

Kilojoules on a food label may need conversion to the kilocalorie scale used in a diary. The arithmetic changes the energy unit, not the portion size. A daily total requires summing the energy for the portions actually recorded.

### How many kilocalories are in a kilojoule?

One kilojoule is about 0.2390057361 kilocalories. The kilocalorie used on food labels is the thermochemical kilocalorie, exactly 4.184 kJ.

### How do you convert kJ to kcal?

Multiply the number of kilojoules by 0.2390057361. For example, 8700 kJ × 0.2390057361 = 2,079.349904 kcal. To go the other way, divide by 0.2390057361.

### How can I estimate kJ to kcal without a calculator?

Multiply by 0.24. That is 0.4% high of the exact factor 0.2390057361, so 8700 kJ comes out as 2,088 kcal instead of 2,079.3499.

### How accurate is the kilojoules to kilocalories converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “8700 kJ to kcal” is checked against Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions).

### Where does the method come from?

NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B; NIST Handbook 44, Appendix C: General tables of units of measurement; BIPM, The International System of Units (SI Brochure), 9th edition.

## Sources

- [NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44, Appendix C: General tables of units of measurement](https://www.nist.gov/pml/weights-and-measures/publications/nist-handbooks/handbook-44)
- [BIPM, The International System of Units (SI Brochure), 9th edition](https://www.bipm.org/en/publications/si-brochure)