How to Convert Kilocalories to Joules (kcal to J)
Energy conversions link food labels in kJ and kcal, SP Group bills in kWh and air-conditioner capacity in BTU. This guide shows how to convert kilocalories into joules by hand, with examples and a quick-reference table.
The conversion
To convert kilocalories to joules, multiply the value by 4,184. To go the other way, divide by the same number (or multiply by 0.0002390057). For a quick estimate, multiply by about 4,200.
Joules = kilocalories × 4,184
Worked examples
- 3 kcal = 12,552 J
- 12.5 kcal = 52,300 J
- 75 kcal = 313,800 J
Kilocalories to Joules table
| Kilocalories | Joules |
|---|---|
| 1 kcal | 4,184 J |
| 2 kcal | 8,368 J |
| 5 kcal | 20,920 J |
| 10 kcal | 41,840 J |
| 20 kcal | 83,680 J |
| 25 kcal | 104,600 J |
| 50 kcal | 209,200 J |
| 100 kcal | 418,400 J |
| 250 kcal | 1,046,000 J |
| 500 kcal | 2,092,000 J |
| 1,000 kcal | 4,184,000 J |
Common questions
Is kcal to J exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Joules to Kilocalories converter.
Mistakes to avoid
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Background
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
For any value, use the Kilocalories to Joules Converter or browse all energy converters.
Run your own numbers: Kilocalories to Joules Converter