Joule to Kilojoule Converter
Energy · unit-converter
Convert Joule to Kilojoule with fixed input and output units, a step-by-step formula line, and reference tables. Factors are joule-based; food energy uses thermochemical calories. The full Energy Converter also includes MMBtu, toe, thermal kWh, and MeV/GeV.
Calculator
From: Joule (j)
To: Kilojoule (kj)
About Joule
The joule is the SI unit of energy. All other units here are converted through fixed joule equivalents.
About Kilojoule
One kilojoule is 1,000 J. Scientific and engineering contexts often use kJ alongside joules.
How to convert joules to kilojoules
1 joule is equal to 0.001 kilojoule when both are expressed in joule-equivalents:
1 j = (1 J ÷ 1,000 J) kj = 0.001 kj
Each joule is defined as 1 J and each kilojoule as 1,000 J in this tool, so one j equals 1 ÷ 1,000 kj = 0.001 kj.
Let d(j) be the numeric amount in Joule (j), and d(kj) the amount in Kilojoule (kj). Then:
d(kj) = d(j) × (1 / 1,000)
Equivalently, divide by how many j fit into one kj (joules per kj divided by joules per j):
d(kj) = d(j) ÷ 1000
Or: kilojoule = joule ÷ 1000
Examples
Example #1: Convert 1 j to kilojoule
1 j = 1 j × (1/1,000) kj = 0.001 kj
1 j = 1 j ÷ 1000 = 0.001 kj
Example #2: Convert 10 j to kilojoule
10 j = 10 j × (1/1,000) kj = 0.01 kj
10 j = 10 j ÷ 1000 = 0.01 kj
Summary
To convert Joule to Kilojoule, multiply the value in j by the ratio of joules per j divided by joules per kj. Equivalently: value_kj = value_j × (1 / 1000). Numerically, 1 j equals 0.001 kj.
Relationship context
Both units are SI energy (joules). Conversions use fixed joule factors, so results stay consistent with the definitions in this converter. The factor from Joule to Kilojoule is 1.000000e-3 (1 j = 0.001 kj).
Conversion tables
| Joule (j) | Kilojoule (kj) |
|---|---|
| 0.1 | 0.0001 |
| 1 | 0.001 |
| 2 | 0.002 |
| 3 | 0.003 |
| 4 | 0.004 |
| 5 | 0.005 |
| 6 | 0.006 |
| 7 | 0.007 |
| 8 | 0.008 |
| 9 | 0.009 |
| Joule (j) | Kilojoule (kj) |
|---|---|
| 10 | 0.01 |
| 20 | 0.02 |
| 30 | 0.03 |
| 40 | 0.04 |
| 50 | 0.05 |
| 60 | 0.06 |
| 70 | 0.07 |
| 80 | 0.08 |
| 90 | 0.09 |
| 100 | 0.1 |