How to Convert Joules to Kilocalories (J to kcal)
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 joules into kilocalories by hand, with examples and a quick-reference table.
The conversion
To convert joules to kilocalories, multiply the value by 0.0002390057. To go the other way, divide by the same number (or multiply by 4,184). Because the factor is tiny, scientific notation keeps the numbers manageable.
Kilocalories = joules × 0.0002390057
Worked examples
- 3 J = 0.000717 kcal
- 12.5 J = 0.002988 kcal
- 75 J = 0.017925 kcal
Joules to Kilocalories table
| Joules | Kilocalories |
|---|---|
| 1 J | 0.000239 kcal |
| 2 J | 0.000478 kcal |
| 5 J | 0.001195 kcal |
| 10 J | 0.00239 kcal |
| 20 J | 0.00478 kcal |
| 25 J | 0.005975 kcal |
| 50 J | 0.01195 kcal |
| 100 J | 0.023901 kcal |
| 250 J | 0.059751 kcal |
| 500 J | 0.119503 kcal |
| 1,000 J | 0.239006 kcal |
Common questions
Is J to kcal 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 Kilocalories to Joules converter.
Mistakes to avoid
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
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.
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.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For any value, use the Joules to Kilocalories Converter or browse all energy converters.
Run your own numbers: Joules to Kilocalories Converter