A kilocalorie is 1,000 calories.
Kilocalories to Kilojoules Converter — kcal to kJ
Convert Kilocalorie (kcal) to Kilojoule (kJ) using the exact conversion factor (1 kilocalorie = 4.184 kilojoule). See the formula, worked examples, and conversion table.
Kilocalories to Kilojoules converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
Kilojoule is 1000 joule units.
Result = input x 4184 / 1000.
Energy units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Kilocalories to Kilojoules
Kilocalorie and Kilojoule both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. Specifically: A kilocalorie is 1,000 calories, and kilojoule is 1000 joule units.
Formula
kilojoules = kilocalories × 4.184
This factor comes from each unit's defined relationship to the category's base unit: 1 kilocalorie equals 4184 base units, and 1 kilojoule equals 1000 base units, so dividing one by the other gives the direct kilocalorie-to-kilojoule factor of 4.184.
Simple example
1 kcal × 4.184 = 4.184 kJ
1 kilocalorie = 4.184 kilojoules.
Real-world example
100 kcal × 4.184 = 418.4 kJ
100 kilocalories = 418.4 kilojoules.
Conversion table
| Kilocalorie (kcal) | Kilojoule (kJ) |
|---|---|
| 1 kcal | 4.184 kJ |
| 10 kcal | 41.84 kJ |
| 50 kcal | 209.2 kJ |
| 100 kcal | 418.4 kJ |
| 500 kcal | 2,092 kJ |
| 1,000 kcal | 4,184 kJ |
Reverse conversion: Kilojoule to Kilocalorie
4.184 kJ × 0.2390057361 = 1 kcal
4.184 kilojoules = 1 kilocalorie.
kilocalories = kilojoules × 0.239005736138
For a page dedicated to this direction, see Kilojoule to Kilocalorie.
Understanding the Kilocalorie (kcal)
A kilocalorie is 1,000 calories.
Understanding the Kilojoule (kJ)
Kilojoule is 1000 joule units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many kilojoules are in 1 kilocalorie?
1 kilocalorie equals 4.184 kilojoules, using the exact defined conversion factor rather than an estimate.
How do I convert kilocalorie to kilojoule?
Multiply the kilocalorie value by 4.184. The converter above does this instantly to whatever precision you set.
How do I convert kilojoule back to kilocalorie?
Use the reverse factor: 1 kilojoule equals 0.2390057361 kilocalories. You can also use the swap control in the converter above to flip the direction instantly.
What is a kilocalorie?
Kilocalorie (kcal) is a unit of engineering.
What is a kilojoule?
Kilojoule (kJ) is a unit of engineering.
Is the kilocalorie to kilojoule conversion exact?
Yes. Both kilocalorie and kilojoule are defined by fixed standards rather than physical artifacts, so the factor of 4.184 used above is exact to as many digits as you choose to display.
Why do engineering unit conventions vary so much by region and industry?
Pressure, force, and stress can be expressed in metric (pascal, newton), US customary (psi, pound-force), or older and industry-specific units (atmosphere, torr, kip) depending on the country, industry, and even the equipment manufacturer, which is why engineers routinely need to convert between them when working across specs from different sources.