Joules to Calories Converter
Convert joules to calories — 4.184 joules to the small calorie. Results update as you type; exact factors shown.
One joule is 0.239 calorie (thermochemical) — see the exact factor, not a rounded rule of thumb.
How the joules to calories 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 |
|---|---|---|
| 1 J | 0.239 cal | joule to calorie (thermochemical) |
| 10 J | 2.3901 cal | joules to calorie (thermochemical) |
| 100 J | 23.9006 cal | joules to calorie (thermochemical) |
| 418.4 J | 100 cal | joules to calorie (thermochemical) |
| 1,000 J | 239.0057 cal | joules to calorie (thermochemical) |
| 4,184 J | 1,000 cal | joules to calorie (thermochemical) |
| 10,000 J | 2,390.0574 cal | joules to calorie (thermochemical) |
| 100,000 J | 23,900.5736 cal | joules to calorie (thermochemical) |
| 1,000,000 J | 239,005.7361 cal | joules to calorie (thermochemical) |
| 4,184,000 J | 1,000,000 cal | joules to calorie (thermochemical) |
| 8,368,000 J | 2,000,000 cal | joules to calorie (thermochemical) |
| 10,000,000 J | 2,390,057.3614 cal | joules to calorie (thermochemical) |
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 calorie?
4.184 for the small calorie used in physics.
Is a food Calorie different?
Yes — it is a kilocalorie, so 4,184 joules.
How many joules in a 2,000 Calorie diet?
About 8.37 million.
Which unit do food labels use?
Kilojoules in Australia and much of Europe, kilocalories in the US and UK, often both.
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.