A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
Kilojoules to Millijoules
Convert Kilojoule (kJ) to Millijoule (mJ) 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 kilojoules (kJ) to millijoules (mJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
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.
mJ = kJ × 1000000
Results update instantly for Kilojoules to Millijoules conversions.
Reserved above the conversion cards and below the converter.
Formula
mJ = kJ × 1000000
kJ = mJ × 0.000001
Conversion table
| 1 kJ | 1.000000e+06 mJ |
| 5 kJ | 5.000000e+06 mJ |
| 10 kJ | 1.000000e+07 mJ |
| 20 kJ | 2.000000e+07 mJ |
| 50 kJ | 5.000000e+07 mJ |
| 100 kJ | 1.000000e+08 mJ |
| 500 kJ | 5.000000e+08 mJ |
| 1000 kJ | 1.000000e+09 mJ |
Related conversions
Reserved between the cards and the FAQ so the page stays balanced.
How the formula works
Both kilojoule and millijoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in kilojoules by 1000000 to get millijoules. To reverse the conversion, multiply a millijoule value by 0.000001 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 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.
How do I convert kilojoules to millijoules?
Multiply the kilojoule value by 1000000 to get the equivalent in millijoules. For example, 5 kJ × 1000000 = 5.000000e+06 mJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 1000000 is an exact, non-rounded value.
Can I convert millijoules back to kilojoules?
Yes. Divide the millijoule value by 1000000, or multiply it by 0.000001, to get kilojoules.
Reserved between the FAQ and the article so the page stays balanced.
About converting kilojoules to millijoules
A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States. 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.
Use this calculator to move between kilojoules and millijoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.