Kilojoule is 1000 joule units.
Kilojoules to Millijoules Converter — kJ to mJ
Convert Kilojoule (kJ) to Millijoule (mJ) using the exact conversion factor (1 kilojoule = 1,000,000 millijoule). See the formula, worked examples, and conversion table.
Kilojoules to Millijoules converter
Converter
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, electronvolts, therms, and mechanical work units.
Context values
Some unit families need one extra value for a physically accurate result.
Millijoule is 0.001 joule units.
Result = input x 1000 / 0.001.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Kilojoules to Millijoules
Kilojoule and Millijoule both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Specifically: Kilojoule is 1000 joule units, and millijoule is 0.001 joule units.
Formula
millijoules = kilojoules × 1000000
This factor comes from each unit's defined relationship to the category's base unit: 1 kilojoule equals 1000 base units, and 1 millijoule equals 0.001 base units, so dividing one by the other gives the direct kilojoule-to-millijoule factor of 1000000.
Simple example
1 kJ × 1000000 = 1,000,000 mJ
1 kilojoule = 1,000,000 millijoules.
Real-world example
100 kJ × 1000000 = 100,000,000 mJ
100 kilojoules = 100,000,000 millijoules.
Conversion table
| Kilojoule (kJ) | Millijoule (mJ) |
|---|---|
| 1 kJ | 1,000,000 mJ |
| 10 kJ | 10,000,000 mJ |
| 100 kJ | 100,000,000 mJ |
| 500 kJ | 500,000,000 mJ |
| 1,000 kJ | 1,000,000,000 mJ |
| 2,000 kJ | 2,000,000,000 mJ |
Reverse conversion: Millijoule to Kilojoule
1 mJ × 0.000001 = 0.000001 kJ
1 millijoule = 0.000001 kilojoules.
kilojoules = millijoules × 0.000001
For a page dedicated to this direction, see Millijoule to Kilojoule.
Understanding the Kilojoule (kJ)
Kilojoule is 1000 joule units.
Understanding the Millijoule (mJ)
Millijoule is 0.001 joule units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many millijoules are in 1 kilojoule?
1 kilojoule equals 1,000,000 millijoules, using the exact defined conversion factor rather than an estimate.
How do I convert kilojoule to millijoule?
Multiply the kilojoule value by 1000000. The converter above does this instantly to whatever precision you set.
How do I convert millijoule back to kilojoule?
Use the reverse factor: 1 millijoule equals 0.000001 kilojoules. You can also use the swap control in the converter above to flip the direction instantly.
What is a kilojoule?
Kilojoule (kJ) is a unit of energy.
What is a millijoule?
Millijoule (mJ) is a unit of energy.
Is the kilojoule to millijoule conversion exact?
Yes. Both kilojoule and millijoule are defined by fixed standards rather than physical artifacts, so the factor of 1000000 used above is exact to as many digits as you choose to display.