Calories to Kilojoules Converter
Enter the energy in calories below to convert it to kilojoules.
Convert Calories to Kilojoules
Enter a value in calories (cal) to convert to kilojoules (kJ).
Gram Calorie to Kilojoule Conversion Table
Table showing various gram calorie measurements converted to kilojoules. Click any preset value or arrow to load it into the converter.
| Calories (cal) | Kilojoules (kJ) |
|---|---|
| 1 cal | 0.004184 kJ |
| 2 cal | 0.008368 kJ |
| 2.5 cal | 0.01046 kJ |
| 5 cal | 0.02092 kJ |
| 10 cal | 0.04184 kJ |
| 15 cal | 0.06276 kJ |
| 20 cal | 0.08368 kJ |
| 25 cal | 0.1046 kJ |
| 30 cal | 0.12552 kJ |
| 50 cal | 0.2092 kJ |
How to Convert Calories to Kilojoules
To convert calories to kilojoules, multiply the energy by the following conversion ratio: 0.004184 kilojoules/gram calorie.
Since one gram calorie is equal to 0.004184 kilojoules, you can use this simple formula to convert:
The energy in kilojoules is equal to the energy in calories multiplied by 0.004184.
For example, here's how to convert 5 calories to kilojoules using the formula above.
How Many Kilojoules Are in a Gram Calorie?
There are 0.004184 kilojoules in a gram calorie, which is why we use this value in the formula above.
Our gram calorie to kilojoule calculator automatically converts your energy measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Calories and kilojoules are both units used to measure energy. Keep reading to learn more about each unit.
What Is a Gram Calorie?
A gram calorie is a unit of energy equal to 4.184 joules (J), the base unit for energy. Thermochemical gram calorie defined as 4.184 Joules. [1]
The gram calorie is classified as a standard unit of energy. Calories can be abbreviated as cal; for example, 1 gram calorie can be written as 1 cal.
When working with calories (cal) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, calories (cal) are widely used across standard energy applications within international standard workflows, engineering documentation, and technical data sheets.
What Is a Kilojoule?
A kilojoule is a unit of energy equal to 1,000 joules (J), the base unit for energy. Equal to 1,000 Joules. [2]
The kilojoule is classified as a metric and SI-compatible unit of energy. Kilojoules can be abbreviated as kJ; for example, 1 kilojoule can be written as 1 kJ.
In the metric system, "kilo" is the standard SI prefix for thousands, or 10³. This makes the kilojoule (kJ) a convenient decimal multiple of the joule (J).
In practice, kilojoules (kJ) are widely used across large-scale industrial, bulk, and macro-level energy specifications within SI metric workflows, engineering documentation, and technical data sheets.
When converting energy between calories (cal) and kilojoules (kJ), keep full floating-point precision (1 cal = 0.004184 kJ; 1 kJ = 239.0057361 cal) during intermediate calculations and round only the final kilojoule figure to match your instrument tolerance.
More Gram Calorie & Kilojoule Conversions
Need to calculate in the opposite direction? Use our kilojoules to calories calculator to switch your starting unit immediately. You can also explore related tools such as converting kilojoules to calories, converting joules to kilojoules, or converting kilocalories to kilojoules.
Convert from Calories
Frequently Asked Questions
References
- [1]NIST CODATA StandardNIST CODATA (CODATA Energy & Thermodynamic Constants)·Energy Metrology Standard — Calories (cal) to Kilojoules (kJ)
- [2]NIST SP 811 SpecificationNIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Gram Calorie (cal) (cal) & Kilojoule (kJ)
- [3]BIPM ReferenceBIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (cal to kJ)