A zeptojoule (zJ) is a metric-prefixed unit of energy equal to 10-21 joules, a fraction of a single joule, using the SI zepto prefix.
Zeptojoules to Joules
Convert Zeptojoule (zJ) to Joule (J) instantly with an exact formula, conversion table, and FAQ.
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Convert zeptojoules (zJ) to joules (J) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
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.
J = zJ × 1.000000000e-21
Results update instantly for Zeptojoules to Joules conversions.
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Formula
J = zJ × 1.000000000e-21
zJ = J × 1.000000000e+21
Conversion table
| 1 zJ | 1.000000e-21 J |
| 5 zJ | 5.000000e-21 J |
| 10 zJ | 1.000000e-20 J |
| 20 zJ | 2.000000e-20 J |
| 50 zJ | 5.000000e-20 J |
| 100 zJ | 1.000000e-19 J |
| 500 zJ | 5.000000e-19 J |
| 1000 zJ | 1.000000e-18 J |
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How the formula works
Both zeptojoule and joule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in zeptojoules by 1.000000000e-21 to get joules. To reverse the conversion, multiply a joule value by 1.000000000e+21 to get back to zeptojoules.
Frequently asked questions
What is Zeptojoule (zJ)?
A zeptojoule (zJ) is a metric-prefixed unit of energy equal to 10-21 joules, a fraction of a single joule, using the SI zepto prefix.
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.
How do I convert zeptojoules to joules?
Multiply the zeptojoule value by 1.000000000e-21 to get the equivalent in joules. For example, 5 zJ × 1.000000000e-21 = 5.000000e-21 J.
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 joules back to zeptojoules?
Yes. Divide the joule value by 1.000000000e-21, or multiply it by 1.000000000e+21, to get zeptojoules.
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About converting zeptojoules to joules
A zeptojoule (zJ) is a metric-prefixed unit of energy equal to 10-21 joules, a fraction of a single joule, using the SI zepto prefix. 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.
Use this calculator to move between zeptojoules and joules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.