A kilocalorie is 1,000 calories.
Kilocalories to Gigajoules Converter — kcal to GJ
Convert Kilocalorie (kcal) to Gigajoule (GJ) using the exact conversion factor (1 kilocalorie = 0.000004184 gigajoule). See the formula, worked examples, and conversion table.
Kilocalories to Gigajoules 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.
Gigajoule is 1000000000 joule units.
Result = input x 4184 / 1e+9.
Energy units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Kilocalories to Gigajoules
Kilocalorie and Gigajoule 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 gigajoule is 1000000000 joule units.
Formula
gigajoules = kilocalories × 0.000004184
This factor comes from each unit's defined relationship to the category's base unit: 1 kilocalorie equals 4184 base units, and 1 gigajoule equals 1000000000 base units, so dividing one by the other gives the direct kilocalorie-to-gigajoule factor of 0.000004184.
Simple example
1 kcal × 0.000004184 = 0.000004184 GJ
1 kilocalorie = 0.000004184 gigajoules.
Real-world example
100 kcal × 0.000004184 = 0.0004184 GJ
100 kilocalories = 0.0004184 gigajoules.
Conversion table
| Kilocalorie (kcal) | Gigajoule (GJ) |
|---|---|
| 1 kcal | 0.000004184 GJ |
| 10 kcal | 0.00004184 GJ |
| 50 kcal | 0.0002092 GJ |
| 100 kcal | 0.0004184 GJ |
| 500 kcal | 0.002092 GJ |
| 1,000 kcal | 0.004184 GJ |
Reverse conversion: Gigajoule to Kilocalorie
0.000004184 GJ × 239005.7361 = 1 kcal
0.000004184 gigajoules = 1 kilocalorie.
kilocalories = gigajoules × 239005.736138
For a page dedicated to this direction, see Gigajoule to Kilocalorie.
Understanding the Kilocalorie (kcal)
A kilocalorie is 1,000 calories.
Understanding the Gigajoule (GJ)
Gigajoule is 1000000000 joule units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many gigajoules are in 1 kilocalorie?
1 kilocalorie equals 0.000004184 gigajoules, using the exact defined conversion factor rather than an estimate.
How do I convert kilocalorie to gigajoule?
Multiply the kilocalorie value by 0.000004184. The converter above does this instantly to whatever precision you set.
How do I convert gigajoule back to kilocalorie?
Use the reverse factor: 1 gigajoule equals 239,005.7361 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 gigajoule?
Gigajoule (GJ) is a unit of engineering.
Is the kilocalorie to gigajoule conversion exact?
Yes. Both kilocalorie and gigajoule are defined by fixed standards rather than physical artifacts, so the factor of 0.000004184 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.