Convert Kilocalories to Kilojoules
Kilocalories to kilojoules is the conversion you need when a food label lists Calories but you want the kilojoule figure used on many nutrition panels. One kilocalorie is exactly 4.184 kilojoules, so the kilojoule number always comes out larger.
Kilocalories to Kilojoules conversion table
| Kilocalories (kcal) | Kilojoules (kJ) |
|---|---|
| 1 | 4.184 |
| 2 | 8.368 |
| 3 | 12.552 |
| 5 | 20.92 |
| 10 | 41.84 |
| 20 | 83.68 |
| 50 | 209.2 |
| 100 | 418.4 |
| 500 | 2,092 |
| 1,000 | 4,184 |
The formula
To convert kilocalories to kilojoules, multiply the number of kilocalories by 4.184:
kilojoules = kilocalories × 4.184
A worked example
Say you have a 250-Calorie snack — 250 kcal — and want it in kilojoules:
250 × 4.184 = 1046 kJ
So a 250-Calorie snack is exactly 1046 kilojoules.
Why the number is exact
A "kilocalorie" (kcal) is the "Calorie" you see on food nutrition labels — one food Calorie is one kilocalorie. It's built on the thermochemical calorie, which is defined as exactly 4.184 joules. A kilocalorie is 1000 of those joules, which is exactly 4.184 kilojoules — a fixed definition, not a rounded measurement. That's why many nutrition panels can print both the Calorie and the kilojoule figure side by side.
When you'll use it
Reading a nutrition label that lists kilojoules instead of Calories, comparing food energy on labels from different countries, and switching a diet or fitness figure into the kilojoule unit.
Frequently asked questions
How many kilojoules are in a kilocalorie?
Exactly 4.184 kilojoules. A kilocalorie uses the thermochemical calorie, defined as exactly 4.184 joules, so a kilocalorie works out to exactly 4.184 kilojoules.
Is a kilocalorie the same as a food Calorie?
Yes. The 'Calorie' with a capital C on a nutrition label is a kilocalorie — one food Calorie is one kilocalorie. That's why a 250-Calorie snack is exactly 1046 kilojoules.
Is the kilocalories to kilojoules conversion exact?
Yes. The thermochemical calorie is defined as exactly 4.184 joules, so a kilocalorie is exactly 4.184 kilojoules — nothing is rounded away.