Joules to Kilojoules Converter
Convert joules to kilojoules — divide by a thousand. Results update as you type; exact factors shown.
One joule is 0.001 kilojoules — see the exact factor, not a rounded rule of thumb.
How the joules to kilojoules converter works
Energy converts through the joule. A thermochemical calorie is exactly 4.184 J, so a food Calorie (kcal) is 4.184 kJ. A kilowatt-hour is exactly 3.6 MJ. A BTU is 1,055.056 J and a US therm is 100,000 BTU.
Australia is fully metric under the National Measurement Act 1960; imperial units appear only in trade with the US and in older documents.
Common energy conversions
| From | To | Units |
|---|---|---|
| 100 J | 0.1 kJ | joules to kilojoules |
| 500 J | 0.5 kJ | joules to kilojoules |
| 1,000 J | 1 kJ | joules to kilojoules |
| 2,000 J | 2 kJ | joules to kilojoules |
| 5,000 J | 5 kJ | joules to kilojoules |
| 10,000 J | 10 kJ | joules to kilojoules |
| 50,000 J | 50 kJ | joules to kilojoules |
| 100,000 J | 100 kJ | joules to kilojoules |
| 500,000 J | 500 kJ | joules to kilojoules |
| 1,000,000 J | 1,000 kJ | joules to kilojoules |
| 3,600,000 J | 3,600 kJ | joules to kilojoules |
| 10,000,000 J | 10,000 kJ | joules to kilojoules |
Units in this converter and their exact factors
| Unit | Symbol | One unit in joules |
|---|---|---|
| joule | J | 1 joule |
| kilojoule | kJ | 1,000 joule |
| megajoule | MJ | 1,000,000 joule |
| calorie (thermochemical) | cal | 4.184 joule |
| kilocalorie (food Calorie) | kcal | 4,184 joule |
| watt-hour | Wh | 3,600 joule |
| kilowatt-hour | kWh | 3,600,000 joule |
| British thermal unit | BTU | 1,055.05585262 joule |
| therm (US) | thm | 105,505,585.262 joule |
| foot-pound | ft·lb | 1.3558179483 joule |
FAQFrequently asked questions about energy conversion
How many joules in a kilojoule?
Exactly 1,000.
What is 1 kWh in kJ?
3,600 kJ.
Where are kilojoules used?
Nutrition labels outside the US, and thermodynamics.
What is a food Calorie in kJ?
4.184 kJ — the capital-C Calorie is a kilocalorie.
What is 1,000,000 J?
One megajoule, or 1,000 kJ.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Measurement Institute (NMI) — Australia's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.