Joules to Kilocalories Converter
Enter the energy in joules below to convert it to kilocalories.
Convert Joules to Kilocalories
Enter a value in joules (J) to convert to kilocalories (kcal).
Joule to Kilocalorie Conversion Table
Table showing various joule measurements converted to kilocalories. Click any preset value or arrow to load it into the converter.
| Joules (J) | Kilocalories (kcal) |
|---|---|
| 1 J | 0.000239006 kcal |
| 2 J | 0.000478011 kcal |
| 2.5 J | 0.000597514 kcal |
| 5 J | 0.001195 kcal |
| 10 J | 0.0023901 kcal |
| 15 J | 0.0035851 kcal |
| 20 J | 0.0047801 kcal |
| 25 J | 0.0059751 kcal |
| 30 J | 0.0071702 kcal |
| 50 J | 0.0119503 kcal |
How to Convert Joules to Kilocalories
To convert joules to kilocalories, multiply the energy by the following conversion ratio: 0.000239006 kilocalories/joule.
Since one joule is equal to 0.000239006 kilocalories, you can use this simple formula to convert:
The energy in kilocalories is equal to the energy in joules multiplied by 0.000239006.
For example, here's how to convert 5 joules to kilocalories using the formula above.
How Many Kilocalories Are in a Joule?
There are 0.000239006 kilocalories in a joule, which is why we use this value in the formula above.
Our joule to kilocalorie calculator automatically converts your energy measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Joules and kilocalories are both units used to measure energy. Keep reading to learn more about each unit.
What Is a Joule?
Coherent SI unit of energy and work (1 W·s = 1 N·m). It serves as a primary reference unit for measuring energy across scientific and practical applications. [1]
The joule is classified as an International System of Units (SI) unit of energy. Joules can be abbreviated as J; for example, 1 joule can be written as 1 J.
As the primary coherent reference unit for energy in this category, all other energy units are mathematically anchored to the joule (J).
In practice, joules (J) are widely used across standard energy applications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.
What Is a Kilocalorie?
A kilocalorie is a unit of energy equal to 4,184 joules (J), the base unit for energy. Dietary Calorie equal to 1,000 small calories (4,184 Joules). [2]
The kilocalorie is classified as a standard unit of energy. Kilocalories can be abbreviated as kcal; for example, 1 kilocalorie can be written as 1 kcal.
In the metric system, "kilo" is the standard SI prefix for thousands, or 10³. This makes the kilocalorie (kcal) a convenient decimal multiple of the calorie (cal).
In practice, kilocalories (kcal) are widely used across large-scale industrial, bulk, and macro-level energy specifications within international standard workflows, engineering documentation, and technical data sheets.
When converting energy between joules (J) and kilocalories (kcal), keep full floating-point precision (1 J = 0.000239006 kcal; 1 kcal = 4,184 J) during intermediate calculations and round only the final kilocalorie figure to match your instrument tolerance.
More Joule & Kilocalorie Conversions
Need to calculate in the opposite direction? Use our kilocalories to joules calculator to switch your starting unit immediately. You can also explore related tools such as converting kilocalories to joules, converting calories to kilocalories, or converting kilojoules to kilocalories.
Convert from Joules
Frequently Asked Questions
References
- [1]NIST CODATA StandardNIST CODATA (CODATA Energy & Thermodynamic Constants)·Energy Metrology Standard — Joules (J) to Kilocalories (kcal)
- [2]NIST SP 811 SpecificationNIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Joule (J) & Kilocalorie (Food Calorie) (kcal)
- [3]BIPM ReferenceBIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (J to kcal)