Joule to Kilojoule (J to kJ)
Result
0.001 Kilojoule
Formula
kJ = J × 0.001
1 J = 0.001 kJ, and 1 kJ = 1,000 J.
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 J × 0.001 = 0.001 kJ
- 10 J × 0.001 = 0.01 kJ
- 100 J × 0.001 = 0.1 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.
Joule to Kilojoule table
| Joule (J) | Kilojoule (kJ) |
|---|---|
| 1 | 0.001 |
| 2 | 0.002 |
| 5 | 0.005 |
| 10 | 0.01 |
| 20 | 0.02 |
| 50 | 0.05 |
| 100 | 0.1 |
| 1,000 | 1 |
The units
- Joule (J)
- A unit of energy.
- 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