Calorie to Kilojoule Converter
Convert calories (kcal) to kilojoules (kJ) and joules (J) instantly. Perfect for nutrition tracking and physics calculations.
Energy Converter
Calories vs Kilojoules
Calories (kcal)
Commonly used in nutrition in the US and UK. It measures the amount of energy needed to raise the temperature of 1kg of water by 1°C.
Kilojoules (kJ)
The International System of Units (SI) unit for energy. Mandatory for food labeling in many countries including Australia, NZ, and the EU.
Energy Insights
The Large Calorie
What we call a "calorie" in food is actually a kilocalorie (kcal). 1 kcal = 1,000 small calories.
Joules vs Calories
The Joule is the SI unit of energy. Calories are still widely used in nutrition but kJ is mandatory in many countries.
Energy Density
Fat contains about 9 kcal/g, while carbohydrates and proteins contain about 4 kcal/g.
Conversion Formulas
Calories to kJ
kJ = kcal * 4.184Example: 100 kcal * 4.184 = 418.4 kJ
kJ to Calories
kcal = kJ / 4.184Example: 500 kJ / 4.184 = 119.5 kcal
Reference Table
| Calories (kcal) | Kilojoules (kJ) | Joules (J) |
|---|---|---|
| 1 kcal | 4.18 kJ | 4184 J |
| 10 kcal | 41.84 kJ | 41840 J |
| 50 kcal | 209.20 kJ | 209200 J |
| 100 kcal | 418.40 kJ | 418400 J |
| 500 kcal | 2092.00 kJ | 2092000 J |
| 1000 kcal | 4184.00 kJ | 4184000 J |
| 2000 kcal | 8368.00 kJ | 8368000 J |
| 5000 kcal | 20920.00 kJ | 20920000 J |
Overview & Capabilities
Convert calories (kcal) to kilojoules (kJ) and joules (J) instantly. Perfect for nutrition tracking and physics calculations.
How to Use
Key Features
Frequently Asked Questions
Q What is the formula for converting calories to kJ?
Multiply the calorie value by 4.184.
Q What is the difference between a calorie and a kilocalorie?
In nutrition, "calorie" usually refers to a kilocalorie (kcal), which is 1,000 small calories.
Q Is a kilojoule bigger than a calorie?
No, 1 calorie is larger than 1 joule. Specifically, 1 calorie equals about 4.184 joules. However, a kilojoule (1,000 joules) is larger than a single calorie.
Q Why do some countries use kJ instead of calories?
Kilojoules are the International System of Units (SI) measurement for energy. Many countries, including Australia, New Zealand, and the EU, use kJ on food labels to align with SI standards.
Q How do I convert kJ to calories manually?
To convert kilojoules to calories, divide the kJ value by 4.184.
Q What is a joule?
A joule is the base unit of energy in the International System of Units. One kilojoule (kJ) equals 1,000 joules (J).