Convert Kilojoules to Calories
Convert Kilojoules (kJ) to Calories (cal) instantly and accurately.
Conversion Formula
cal = kJ × 239.0057361
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 Calories
A calorie (cal) - the thermochemical calorie - is exactly 4.184 J, defined as the heat to raise 1 g of water by 1°C. Standard since 1954. The calorie is the fundamental unit of heat measurement in thermochemistry: glucose combustion releases 669.9 kcal/mol; water vaporisation requires 539.7 cal/g. Bond dissociation energies in quantum chemistry are often quoted in kcal/mol. Note: the dietary Calorie (capital C) on food labels is 1 kcal = 4,184 J - a factor-of-1,000 difference that causes persistent confusion. 1 cal = 4.184 J = 1.163 × 10⁻³ Wh.
Quick Reference Table
| Kilojoules (kJ) | Calories (cal) |
|---|---|
| 1 kJ | 239.006 cal |
| 2 kJ | 478.011 cal |
| 5 kJ | 1195.03 cal |
| 10 kJ | 2390.06 cal |
| 25 kJ | 5975.14 cal |
| 50 kJ | 11950.3 cal |
| 100 kJ | 23900.6 cal |