Kilocalories to Joules (kcal to J) Converter
1 kilocalorie equals 4,184 joules — multiply kilocalories by 4,184 to convert kcal to J. This uses the thermochemical/food kilocalorie, defined as exactly 4,184 joules.
The formula
To convert kilocalories to joules, multiply by the exact factor:
J = kcal × 4,184
For example, 250 kcal × 4,184 = 1,046,000 J. The factor comes from the definition 1 kcal = 1,000 cal and 1 cal = 4.184 J.
Conversion table
| Kilocalories (kcal) | Joules (J) |
|---|---|
| 1 | 4,184 |
| 2 | 8,368 |
| 5 | 20,920 |
| 10 | 41,840 |
| 25 | 104,600 |
| 50 | 209,200 |
| 100 | 418,400 |
| 500 | 2,092,000 |
| 1000 | 4,184,000 |
How to convert online
- Type the number of kilocalories into the first box.
- Read the joule result instantly in the second box.
- Or enter a joule value to convert back to kilocalories — it works both ways.
Use the Kilocalorie to Joule Converter — free and instant in your browser.
Where this conversion is used
Nutrition data is reported in kilocalories, but physics, chemistry and exercise-science calculations use joules, the SI unit of energy. Converting kcal to J is essential when you compute the energy expenditure of an activity, translate a food's calorie content into scientific units, or check thermochemistry problems that mix the two systems.
FAQ
How many joules are in a kilocalorie?
One kilocalorie equals 4,184 joules using the thermochemical definition.
Why 4,184 and not 4,186?
4,184 J is the thermochemical kilocalorie used in nutrition. The slightly larger 4,186 J value is the "international steam table" calorie; nutrition labels use 4,184.
How do I convert joules back to kilocalories?
Divide the joule value by 4,184 (or multiply by 0.00023901). For example, 41,840 J = 10 kcal.
Is the conversion exact?
Yes. The thermochemical kilocalorie is defined as exactly 4,184 joules.
Related converters
- Joule to Kilocalorie Converter
- Kilocalorie to Kilojoule Converter
- Kilocalorie to Calorie Converter
- Kilocalorie to Watt-hour Converter
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