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 Kilojoules
Convert Millijoule (mJ) to Kilojoule (kJ) instantly with an exact formula, conversion table, and FAQ.
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Convert millijoules (mJ) 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 = mJ × 0.000001
Results update instantly for Millijoules to Kilojoules conversions.
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Formula
kJ = mJ × 0.000001
mJ = kJ × 1000000
Conversion table
| 1 mJ | 0.000001 kJ |
| 5 mJ | 0.000005 kJ |
| 10 mJ | 0.000010 kJ |
| 20 mJ | 0.000020 kJ |
| 50 mJ | 0.000050 kJ |
| 100 mJ | 0.000100 kJ |
| 500 mJ | 0.000500 kJ |
| 1000 mJ | 0.001000 kJ |
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How the formula works
Both millijoule and kilojoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in millijoules by 0.000001 to get kilojoules. To reverse the conversion, multiply a kilojoule value by 1000000 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 Kilojoule (kJ)?
A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
How do I convert millijoules to kilojoules?
Multiply the millijoule value by 0.000001 to get the equivalent in kilojoules. For example, 5 mJ × 0.000001 = 0.000005 kJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 0.000001 is an exact, non-rounded value.
Can I convert kilojoules back to millijoules?
Yes. Divide the kilojoule value by 0.000001, or multiply it by 1000000, to get millijoules.
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About converting millijoules to kilojoules
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 kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
Use this calculator to move between millijoules 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.