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 Attojoules
Convert Zeptojoule (zJ) to Attojoule (aJ) instantly with an exact formula, conversion table, and FAQ.
Reserved for a responsive leaderboard above the conversion details.
Professional calculator style
World-scale conversion engine
30+ categories
6,500+ units
Instant results
Offline ready
Energy calculator
Energy Converter
Convert zeptojoules (zJ) to attojoules (aJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
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.
aJ = zJ × 0.001
Results update instantly for Zeptojoules to Attojoules conversions.
Reserved above the conversion cards and below the converter.
Formula
aJ = zJ × 0.001
zJ = aJ × 1000
Conversion table
| 1 zJ | 0.001000 aJ |
| 5 zJ | 0.005000 aJ |
| 10 zJ | 0.010000 aJ |
| 20 zJ | 0.020000 aJ |
| 50 zJ | 0.050000 aJ |
| 100 zJ | 0.100000 aJ |
| 500 zJ | 0.500000 aJ |
| 1000 zJ | 1 aJ |
Related conversions
Reserved between the cards and the FAQ so the page stays balanced.
How the formula works
Both zeptojoule and attojoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in zeptojoules by 0.001 to get attojoules. To reverse the conversion, multiply a attojoule value by 1000 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 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.
How do I convert zeptojoules to attojoules?
Multiply the zeptojoule value by 0.001 to get the equivalent in attojoules. For example, 5 zJ × 0.001 = 0.005000 aJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 0.001 is an exact, non-rounded value.
Can I convert attojoules back to zeptojoules?
Yes. Divide the attojoule value by 0.001, or multiply it by 1000, to get zeptojoules.
Reserved between the FAQ and the article so the page stays balanced.
About converting zeptojoules to attojoules
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. 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.
Use this calculator to move between zeptojoules and attojoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.