Convert Kilojoules to Kilocalories
Convert Kilojoules (kJ) to Kilocalories (kcal) instantly and accurately.
Conversion Formula
kcal = kJ × 0.2390057361
About Kilojoules
A kilojoule (kJ) is exactly 1,000 J and is the standard energy unit for food and physical chemistry. EU, Australian, and NZ food labels are mandatory in kJ: recommended adult intake is ~8,400 kJ/day. Bond dissociation energies: C-H bond 413 kJ/mol; C=C double bond 614 kJ/mol; N≡N triple bond 945 kJ/mol. Specific heat of water: 4.184 kJ/(kg·K). A cyclist riding at 150 W for one hour expends 540 kJ. Charpy and Izod impact toughness tests record results in J and kJ. 1 kJ = 1,000 J = 239.0 cal = 0.94782 BTU = 0.27778 Wh.
About Kilocalories
A kilocalorie (kcal) - the food Calorie (capital C) on US and Canadian nutrition labels - is exactly 4,184 J. WHO recommends ~2,000-2,500 kcal/day for adults. Energy density of nutrients: fat 9 kcal/g, carbohydrate 4 kcal/g, protein 4 kcal/g, ethanol 7 kcal/g. Running at 10 km/h burns ~600-800 kcal/h. Standard free energy of ATP hydrolysis is approximately −7.3 kcal/mol (−30.5 kJ/mol). Pre-SI thermodynamic tables in the US and Japan use kcal/mol for reaction enthalpies. 1 kcal = 4,184 J = 4.184 kJ = 3.968 BTU = 1.163 Wh.
Quick Reference Table
| Kilojoules (kJ) | Kilocalories (kcal) |
|---|---|
| 1 kJ | 0.239006 kcal |
| 2 kJ | 0.478011 kcal |
| 5 kJ | 1.19503 kcal |
| 10 kJ | 2.39006 kcal |
| 25 kJ | 5.97514 kcal |
| 50 kJ | 11.9503 kcal |
| 100 kJ | 23.9006 kcal |