A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
Kilojoules to Femtojoules
Convert Kilojoule (kJ) to Femtojoule (fJ) instantly with an exact formula, conversion table, and FAQ.
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Convert kilojoules (kJ) 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 = kJ × 1.000000000e+18
Results update instantly for Kilojoules to Femtojoules conversions.
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Formula
fJ = kJ × 1.000000000e+18
kJ = fJ × 1.000000000e-18
Conversion table
| 1 kJ | 1.000000e+18 fJ |
| 5 kJ | 5.000000e+18 fJ |
| 10 kJ | 1.000000e+19 fJ |
| 20 kJ | 2.000000e+19 fJ |
| 50 kJ | 5.000000e+19 fJ |
| 100 kJ | 1.000000e+20 fJ |
| 500 kJ | 5.000000e+20 fJ |
| 1000 kJ | 1.000000e+21 fJ |
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How the formula works
Both kilojoule and femtojoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in kilojoules by 1.000000000e+18 to get femtojoules. To reverse the conversion, multiply a femtojoule value by 1.000000000e-18 to get back to kilojoules.
Frequently asked questions
What is Kilojoule (kJ)?
A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
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 kilojoules to femtojoules?
Multiply the kilojoule value by 1.000000000e+18 to get the equivalent in femtojoules. For example, 5 kJ × 1.000000000e+18 = 5.000000e+18 fJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 1.000000000e+18 is an exact, non-rounded value.
Can I convert femtojoules back to kilojoules?
Yes. Divide the femtojoule value by 1.000000000e+18, or multiply it by 1.000000000e-18, to get kilojoules.
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About converting kilojoules to femtojoules
A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States. 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 kilojoules 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.