Calories to Kilojoules
A small calorie is the energy to raise 1 gram of water by 1°C, a base unit distinct from the food Calorie (kcal). A kilojoule is 1,000 joules, used on nutrition labels outside the US to state food energy content. 1 cal equals 0.004184 kJ, so converting between them is a matter of multiplying by that fixed factor — type any value into the converter below and both sides update instantly as you type.
Both units belong to energy, measured here against energy's base unit (J) — every other energy unit on this site converts through that same reference point, which is why the table below can also be read as a quick cross-check against nearby values.
Formula
kJ = cal × 0.004184
cal = kJ × ≈239.006
Worked example: 5 cal × 0.004184 = 0.02092 kJ.
Conversion table
| Calorie (cal) | Kilojoule (kJ) |
|---|---|
| 1 cal | 0.004184 kJ |
| 2 cal | 0.008368 kJ |
| 3 cal | 0.012552 kJ |
| 5 cal | 0.02092 kJ |
| 10 cal | 0.04184 kJ |
| 20 cal | 0.08368 kJ |
| 25 cal | 0.1046 kJ |
| 50 cal | 0.2092 kJ |
| 100 cal | 0.4184 kJ |
| 250 cal | 1.046 kJ |
| 500 cal | 2.092 kJ |
| 1,000 cal | 4.184 kJ |
Frequently asked
- How many Kilojoules in a calorie?
- 1 cal equals 0.004184 kJ.
- How do I convert Calories to Kilojoules?
- Multiply the value in cal by 0.004184 to get kJ. The converter above does this instantly as you type.
- Is the conversion exact?
- Yes — Calorie and Kilojoule are both defined by a fixed conversion factor to energy's base unit (J), so the result shown is exact to the precision displayed, not an approximation.