A attojoule (aJ) is a metric-prefixed unit of energy equal to 10-18 joules, a fraction of a single joule, using the SI atto prefix.
Attojoules to Kilojoules
Convert Attojoule (aJ) to Kilojoule (kJ) instantly with an exact formula, conversion table, and FAQ.
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Convert attojoules (aJ) to kilojoules (kJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
kJ = aJ × 1.000000000e-21
Results update instantly for Attojoules to Kilojoules conversions.
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Formula
kJ = aJ × 1.000000000e-21
aJ = kJ × 1.000000000e+21
Conversion table
| 1 aJ | 1.000000e-21 kJ |
| 5 aJ | 5.000000e-21 kJ |
| 10 aJ | 1.000000e-20 kJ |
| 20 aJ | 2.000000e-20 kJ |
| 50 aJ | 5.000000e-20 kJ |
| 100 aJ | 1.000000e-19 kJ |
| 500 aJ | 5.000000e-19 kJ |
| 1000 aJ | 1.000000e-18 kJ |
Related conversions
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How the formula works
Both attojoule and kilojoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in attojoules by 1.000000000e-21 to get kilojoules. To reverse the conversion, multiply a kilojoule value by 1.000000000e+21 to get back to attojoules.
Frequently asked questions
What is Attojoule (aJ)?
A attojoule (aJ) is a metric-prefixed unit of energy equal to 10-18 joules, a fraction of a single joule, using the SI atto prefix.
What is Kilojoule (kJ)?
A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
How do I convert attojoules to kilojoules?
Multiply the attojoule value by 1.000000000e-21 to get the equivalent in kilojoules. For example, 5 aJ × 1.000000000e-21 = 5.000000e-21 kJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 1.000000000e-21 is an exact, non-rounded value.
Can I convert kilojoules back to attojoules?
Yes. Divide the kilojoule value by 1.000000000e-21, or multiply it by 1.000000000e+21, to get attojoules.
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About converting attojoules to kilojoules
A attojoule (aJ) is a metric-prefixed unit of energy equal to 10-18 joules, a fraction of a single joule, using the SI atto prefix. A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
Use this calculator to move between attojoules and kilojoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.