The joule (J) is the SI derived unit of energy, equal to the work done when a force of one newton acts over one meter.
Joules to Femtojoules
Convert Joule (J) to Femtojoule (fJ) instantly with an exact formula, conversion table, and FAQ.
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Convert joules (J) to femtojoules (fJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
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.
fJ = J × 1000000000000000
Results update instantly for Joules to Femtojoules conversions.
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Formula
fJ = J × 1000000000000000
J = fJ × 1.000000000e-15
Conversion table
| 1 J | 1.000000e+15 fJ |
| 5 J | 5.000000e+15 fJ |
| 10 J | 1.000000e+16 fJ |
| 20 J | 2.000000e+16 fJ |
| 50 J | 5.000000e+16 fJ |
| 100 J | 1.000000e+17 fJ |
| 500 J | 5.000000e+17 fJ |
| 1000 J | 1.000000e+18 fJ |
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How the formula works
Both joule and femtojoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in joules by 1000000000000000 to get femtojoules. To reverse the conversion, multiply a femtojoule value by 1.000000000e-15 to get back to joules.
Frequently asked questions
What is Joule (J)?
The joule (J) is the SI derived unit of energy, equal to the work done when a force of one newton acts over one meter.
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.
How do I convert joules to femtojoules?
Multiply the joule value by 1000000000000000 to get the equivalent in femtojoules. For example, 5 J × 1000000000000000 = 5.000000e+15 fJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 1000000000000000 is an exact, non-rounded value.
Can I convert femtojoules back to joules?
Yes. Divide the femtojoule value by 1000000000000000, or multiply it by 1.000000000e-15, to get joules.
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About converting joules to femtojoules
The joule (J) is the SI derived unit of energy, equal to the work done when a force of one newton acts over one meter. 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.
Use this calculator to move between joules and femtojoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.