A millijoule (mJ) is a metric-prefixed unit of energy equal to 10-3 joules, a fraction of a single joule, using the SI milli prefix.
Millijoules to Zeptojoules
Convert Millijoule (mJ) to Zeptojoule (zJ) 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 millijoules (mJ) to zeptojoules (zJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
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.
zJ = mJ × 1.000000000e+18
Results update instantly for Millijoules to Zeptojoules conversions.
Reserved above the conversion cards and below the converter.
Formula
zJ = mJ × 1.000000000e+18
mJ = zJ × 1.000000000e-18
Conversion table
| 1 mJ | 1.000000e+18 zJ |
| 5 mJ | 5.000000e+18 zJ |
| 10 mJ | 1.000000e+19 zJ |
| 20 mJ | 2.000000e+19 zJ |
| 50 mJ | 5.000000e+19 zJ |
| 100 mJ | 1.000000e+20 zJ |
| 500 mJ | 5.000000e+20 zJ |
| 1000 mJ | 1.000000e+21 zJ |
Related conversions
Reserved between the cards and the FAQ so the page stays balanced.
How the formula works
Both millijoule and zeptojoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in millijoules by 1.000000000e+18 to get zeptojoules. To reverse the conversion, multiply a zeptojoule value by 1.000000000e-18 to get back to millijoules.
Frequently asked questions
What is Millijoule (mJ)?
A millijoule (mJ) is a metric-prefixed unit of energy equal to 10-3 joules, a fraction of a single joule, using the SI milli prefix.
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.
How do I convert millijoules to zeptojoules?
Multiply the millijoule value by 1.000000000e+18 to get the equivalent in zeptojoules. For example, 5 mJ × 1.000000000e+18 = 5.000000e+18 zJ.
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 zeptojoules back to millijoules?
Yes. Divide the zeptojoule value by 1.000000000e+18, or multiply it by 1.000000000e-18, to get millijoules.
Reserved between the FAQ and the article so the page stays balanced.
About converting millijoules to zeptojoules
A millijoule (mJ) is a metric-prefixed unit of energy equal to 10-3 joules, a fraction of a single joule, using the SI milli prefix. 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.
Use this calculator to move between millijoules and zeptojoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.