Calorie to Kilojoule (cal to kJ)
Result
0.004184 Kilojoule
Formula
kJ = cal × 0.004184
1 cal = 0.004184 kJ, and 1 kJ = 239.0057361 cal.
The joule is the SI unit of energy. The calorie used here is the thermochemical calorie, exactly 4.184 J; a kilowatt-hour is exactly 3.6 MJ; the BTU is the International Table BTU (1,055.05585262 J).
Worked examples
- 1 cal × 0.004184 = 0.004184 kJ
- 10 cal × 0.004184 = 0.04184 kJ
- 100 cal × 0.004184 = 0.4184 kJ
Common mistakes
- Food "Calories" (capital C) are kilocalories: a 250 Calorie snack contains 250 kcal, or 1,046 kJ.
- kW is power and kWh is energy: a 2 kW heater running for 3 hours uses 6 kWh.
- The International Table calorie (4.1868 J) is slightly larger than the thermochemical calorie (4.184 J); engineering steam tables use the former.
Calorie to Kilojoule table
| Calorie (cal) | Kilojoule (kJ) |
|---|---|
| 1 | 0.004184 |
| 2 | 0.008368 |
| 5 | 0.02092 |
| 10 | 0.04184 |
| 20 | 0.08368 |
| 50 | 0.2092 |
| 100 | 0.4184 |
| 1,000 | 4.184 |
The units
- Calorie (cal)
- 1 Calorie = 4.184 Joule.
- Kilojoule (kJ)
- Kilojoule: 1,000 joules. Food labels in Australia, New Zealand and the EU show kJ.
Sources for these factors
- Guide for the Use of the International System of Units (SP 811), Appendix B: conversion factors — NIST
- The International System of Units (SI Brochure), 9th edition — BIPM
Last reviewed against these sources. An automated check recomputes every factor from its definition on each build. How we check accuracy