Quick answer: 1 Joule in Kilojoule
1 J equals 0.001 kJ. To convert Joule to Kilojoule, multiply by 0.001 using the free calculator above — no signup needed.
Energy & Work units
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About Energy & Work Converter
The Energy & Work Converter converts between 7 different units, including Joule, Kilojoule, Calorie, Kilocalorie (kcal), Watt-hour (Wh). The base unit is the Joule, and every other unit on this page is defined as an exact multiple of it. Type any value into the calculator above to convert instantly — free, unlimited, no signup and nothing to install.
Common equivalents: 1 Joule = 0.001 Kilojoule, 0.239006 Calorie, 0.000239006 Kilocalorie (kcal).
Scale of this category: the smallest unit is the Joule (J) and the largest is the Kilowatt-hour (kWh) (kWh).
Last updated: 2026-09-15
Energy & Work conversion factors
| Unit | Symbol | Value in Joule |
|---|---|---|
| Joule | J | 1 J = 1 J |
| Kilojoule | kJ | 1 kJ = 1000 J |
| Calorie | cal | 1 cal = 4.184 J |
| Kilocalorie (kcal) | kcal | 1 kcal = 4184 J |
| Watt-hour (Wh) | Wh | 1 Wh = 3600 J |
| Kilowatt-hour (kWh) | kWh | 1 kWh = 3600000 J |
| BTU | BTU | 1 BTU = 1055.06 J |
Worked Examples
See exactly how the conversion works with real numbers, step by step.
How much is 1 Joule in Kilojoule?
- Multiply 1 by the conversion factor 0.001
- 1 Joule = 0.001 Kilojoule
How much is 100 Joule in Kilojoule?
- Multiply 100 by the conversion factor 0.001
- 100 Joule = 0.1 Kilojoule
How much is 1000 Joule in Kilojoule?
- Multiply 1000 by the conversion factor 0.001
- 1000 Joule = 1 Kilojoule
Quick Conversion Reference Table
| Joule (J) | Kilojoule (kJ) |
|---|---|
| 1 J (Joule) | 0.001 kJ (Kilojoule) |
| 2 J (Joule) | 0.002 kJ (Kilojoule) |
| 5 J (Joule) | 0.005 kJ (Kilojoule) |
| 10 J (Joule) | 0.01 kJ (Kilojoule) |
| 20 J (Joule) | 0.02 kJ (Kilojoule) |
| 50 J (Joule) | 0.05 kJ (Kilojoule) |
| 100 J (Joule) | 0.1 kJ (Kilojoule) |
| 500 J (Joule) | 0.5 kJ (Kilojoule) |
| 1000 J (Joule) | 1 kJ (Kilojoule) |
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FAQ
How much is 1 Joule in Kilojoule?
1 Joule = 0.001 Kilojoule.
How do I convert Joule to Kilojoule?
Enter your value in Joule into the converter above and the result in Kilojoule appears instantly. 1 J equals 0.001 kJ — just multiply your value by 0.001.
What is the formula for Joule to Kilojoule?
The formula is: value in Kilojoule = value in Joule × 0.001. For example, 100 J × 0.001 = 0.1 kJ.
Is this Joule to Kilojoule converter free and accurate?
Yes. This Joule to Kilojoule converter is 100% free, uses the exact international conversion factor (0.001), and works on any device with no signup.
How do I convert Kilojoule back to Joule?
To convert back, divide by 0.001 (or multiply by 1000). You can also use our dedicated How Many Joule in 1 Kilojoule? page for instant results.
Do I need to download an app or sign up?
No. The converter runs entirely in your browser — nothing to install, no account, no fees. It even keeps working offline once the page has loaded.
Which Energy & Work units are supported?
This converter supports 7 units: Joule, Kilojoule, Calorie, Kilocalorie (kcal), Watt-hour (Wh), Kilowatt-hour (kWh), BTU.