Kilocalories to Joules Converter
Convert kilocalories — food Calories — to joules. One kcal is exactly 4,184 J. Results update as you type; exact factors shown.
One kilocalorie (food Calorie) is 4,184 joules — see the exact factor, not a rounded rule of thumb.
How the kilocalories to joules 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.
The UK is metric for most trade and science but keeps miles, pints, stone and mpg (with the imperial gallon) in daily life.
Common energy conversions
| From | To | Units |
|---|---|---|
| 1 kcal | 4,184 J | kilocalorie (food Calorie) to joules |
| 10 kcal | 41,840 J | kilocalorie (food Calorie) to joules |
| 50 kcal | 209,200 J | kilocalorie (food Calorie) to joules |
| 100 kcal | 418,400 J | kilocalorie (food Calorie) to joules |
| 250 kcal | 1,046,000 J | kilocalorie (food Calorie) to joules |
| 500 kcal | 2,092,000 J | kilocalorie (food Calorie) to joules |
| 1,000 kcal | 4,184,000 J | kilocalorie (food Calorie) to joules |
| 2,000 kcal | 8,368,000 J | kilocalorie (food Calorie) to joules |
| 2,500 kcal | 10,460,000 J | kilocalorie (food Calorie) to joules |
| 3,000 kcal | 12,552,000 J | kilocalorie (food Calorie) to joules |
| 5,000 kcal | 20,920,000 J | kilocalorie (food Calorie) to joules |
| 10,000 kcal | 41,840,000 J | kilocalorie (food Calorie) to joules |
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 kilocalorie?
Exactly 4,184.
Is a kilocalorie a food Calorie?
Yes — the capital-C Calorie on a nutrition label is a kilocalorie.
What is 2,000 kcal in joules?
8.368 million J, or 8.37 MJ.
Why do labels use kJ outside the US?
Because it is the SI unit, and most countries mandate it.
What is 100 kcal?
418,400 J — roughly a small apple.
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 Physical Laboratory (NPL) — United Kingdom's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.