How to use Calories to kJ
- Type a value in calories.
- The result in kilojoules appears instantly.
- Type in the second box to convert the other way.
How to convert calories to kilojoules
Multiply the value in calories by 4.184. Formula: kJ = kcal × 4.184. Example: 10 kcal × 4.184 = 41.84 kJ.
Common calories to kilojoules conversions
5 kcal = 20.92 kJ. 25 kcal = 104.6 kJ. 50 kcal = 209.2 kJ. 100 kcal = 418.4 kJ.
Quick mental math
Quick estimate: multiply by 4.2. 500 Cal ≈ 2,100 kJ (exact: 2,092 kJ).
Where is kcal to kJ conversion used?
Energy conversions are used to read food labels (Calories vs kilojoules), track diet and exercise, compare electricity use in kWh, size heaters and air conditioners in BTU, and in physics and engineering.
What are calories?
A food Calorie (with a capital C) is one kilocalorie, exactly 4.184 kilojoules. It is the energy unit on food labels and fitness trackers in the US and UK.
What are kilojoules?
A kilojoule is 1,000 joules, the SI unit of energy. Food labels in Australia, New Zealand and the EU show energy in kJ.
Calories to kilojoules conversion table
| Calories (kcal) | Kilojoules (kJ) |
|---|---|
| 1 | 4.184 |
| 10 | 41.84 |
| 50 | 209.2 |
| 100 | 418.4 |
| 200 | 836.8 |
| 250 | 1,046 |
| 300 | 1,255.2 |
| 500 | 2,092 |
| 750 | 3,138 |
| 1,000 | 4,184 |
| 1,500 | 6,276 |
| 2,000 | 8,368 |
| 2,500 | 10,460 |
| 5,000 | 20,920 |
Frequently asked questions
How many kilojoules are in 1 calorie?
1 calorie = 4.184 kilojoules (1 kcal = 4.184 kJ).
How many calories are in 1 kilojoule?
1 kilojoule = 0.239006 calories (1 kJ = 0.239006 kcal).
What is 10 kcal in kilojoules?
10 kcal = 41.84 kJ.
What is 100 kcal in kilojoules?
100 kcal = 418.4 kJ.
Is the kcal to kJ conversion exact?
Yes. A food Calorie (kilocalorie) is defined as exactly 4.184 kJ, 1 kWh is exactly 3,600 kJ, and the international BTU is 1,055.05585262 joules. Results are rounded only for display.
Last updated: · Free to use, no sign-up.