A (small) calorie is a thermochemical unit of heat energy equal to 4.184 joules, historically the energy needed to raise 1 gram of water by 1°C.
Calories to Gigajoules
Convert Calorie (cal) to Gigajoule (GJ) instantly with an exact formula, conversion table, and FAQ.
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Convert calories (cal) to gigajoules (GJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
A gigajoule (GJ) is a metric-prefixed unit of energy equal to 109 joules, using the SI giga prefix.
GJ = cal × 4.184000000e-09
Results update instantly for Calories to Gigajoules conversions.
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Formula
GJ = cal × 4.184000000e-09
cal = GJ × 239005736.1
Conversion table
| 1 cal | 4.184000e-09 GJ |
| 5 cal | 2.092000e-08 GJ |
| 10 cal | 4.184000e-08 GJ |
| 20 cal | 8.368000e-08 GJ |
| 50 cal | 2.092000e-07 GJ |
| 100 cal | 4.184000e-07 GJ |
| 500 cal | 0.000002 GJ |
| 1000 cal | 0.000004 GJ |
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How the formula works
Both calorie and gigajoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in calories by 4.184000000e-09 to get gigajoules. To reverse the conversion, multiply a gigajoule value by 239005736.1 to get back to calories.
Frequently asked questions
What is Calorie (cal)?
A (small) calorie is a thermochemical unit of heat energy equal to 4.184 joules, historically the energy needed to raise 1 gram of water by 1°C.
What is Gigajoule (GJ)?
A gigajoule (GJ) is a metric-prefixed unit of energy equal to 109 joules, using the SI giga prefix.
How do I convert calories to gigajoules?
Multiply the calorie value by 4.184000000e-09 to get the equivalent in gigajoules. For example, 5 cal × 4.184000000e-09 = 2.092000e-08 GJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 4.184000000e-09 is an exact, non-rounded value.
Can I convert gigajoules back to calories?
Yes. Divide the gigajoule value by 4.184000000e-09, or multiply it by 239005736.1, to get calories.
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About converting calories to gigajoules
A (small) calorie is a thermochemical unit of heat energy equal to 4.184 joules, historically the energy needed to raise 1 gram of water by 1°C. A gigajoule (GJ) is a metric-prefixed unit of energy equal to 109 joules, using the SI giga prefix.
Use this calculator to move between calories and gigajoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.