A femtojoule (fJ) is a metric-prefixed unit of energy equal to 10-15 joules, a fraction of a single joule, using the SI femto prefix.
Femtojoules to Calories
Convert Femtojoule (fJ) to Calorie (cal) instantly with an exact formula, conversion table, and FAQ.
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Convert femtojoules (fJ) to calories (cal) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
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.
cal = fJ × 2.390057361e-16
Results update instantly for Femtojoules to Calories conversions.
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Formula
cal = fJ × 2.390057361e-16
fJ = cal × 4.184000000e+15
Conversion table
| 1 fJ | 2.390057e-16 cal |
| 5 fJ | 1.195029e-15 cal |
| 10 fJ | 2.390057e-15 cal |
| 20 fJ | 4.780115e-15 cal |
| 50 fJ | 1.195029e-14 cal |
| 100 fJ | 2.390057e-14 cal |
| 500 fJ | 1.195029e-13 cal |
| 1000 fJ | 2.390057e-13 cal |
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How the formula works
Both femtojoule and calorie measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in femtojoules by 2.390057361e-16 to get calories. To reverse the conversion, multiply a calorie value by 4.184000000e+15 to get back to femtojoules.
Frequently asked questions
What is Femtojoule (fJ)?
A femtojoule (fJ) is a metric-prefixed unit of energy equal to 10-15 joules, a fraction of a single joule, using the SI femto prefix.
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.
How do I convert femtojoules to calories?
Multiply the femtojoule value by 2.390057361e-16 to get the equivalent in calories. For example, 5 fJ × 2.390057361e-16 = 1.195029e-15 cal.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 2.390057361e-16 is an exact, non-rounded value.
Can I convert calories back to femtojoules?
Yes. Divide the calorie value by 2.390057361e-16, or multiply it by 4.184000000e+15, to get femtojoules.
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About converting femtojoules to calories
A femtojoule (fJ) is a metric-prefixed unit of energy equal to 10-15 joules, a fraction of a single joule, using the SI femto prefix. 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.
Use this calculator to move between femtojoules and calories accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.