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21 millimeters (mm) = 0.000021 kilometers (km). To convert 21 mm to km, divide the length value by the conversion factor 1000000.
Number of millimeters ÷ 1000000 = Value in kilometers
21 mm = 21 ÷ 1000000 = 0.000021 km
| Millimeters [mm] | Kilometers [km] |
| 21 | 0.000021 |
| 22 | 0.000022 |
| 23 | 0.000023 |
| 24 | 0.000024 |
| 25 | 0.000025 |
| 26 | 0.000026 |
| 27 | 0.000027 |
| 28 | 0.000028 |
| 29 | 0.000029 |
| 30 | 0.00003 |
| 31 | 0.000031 |
| 32 | 0.000032 |
| 33 | 0.000033 |
| 34 | 0.000034 |
| 35 | 0.000035 |
| 36 | 0.000036 |
| 37 | 0.000037 |
| 38 | 0.000038 |
| 39 | 0.000039 |
| 40 | 0.00004 |
How many kilometers are there in a millimeter?
There are 0.000001 kilometers in a millimeter.
Which is the bigger unit?
Kilometer is the bigger unit than millimeter.