Length and Area
mmtokm
Convert millimetres (mm) to kilometres (km).
Factor1 mm = 1e-6 km
Converter
mm
Accepts numbers or expressions, e.g. 150 + 14.7
Result
km
Rendered to 6 significant figures.
Formula
Formula
km = mm × 1e-6
Multiply any value in millimetres by 1e-6 to obtain the value in kilometres.
Worked example
Convert 1.00000e+6 mm to km.
- 01Start with 1.00000e+6 mm.
- 02Multiply by the conversion factor: 1.00000e+6 × 1e-6 = 1 km.
Result1.00000e+6 mm = 1 km
Conversion table
| mm | km |
|---|---|
| 1 | 1e-6 |
| 2 | 2e-6 |
| 5 | 5e-6 |
| 10 | 1e-5 |
| 20 | 2e-5 |
| 50 | 5e-5 |
| 100 | 0.0001 |
| 200 | 0.0002 |
| 500 | 0.0005 |
| 1000 | 0.001 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from mm to km?
1 mm equals 1e-6 km. To convert, multiply the value in millimetres by 1e-6.
How do I convert 1 mm to km?
1 mm = 1e-6 km. For any value, multiply by 1e-6.
How do I convert km back to mm?
Divide by the same factor — or equivalently, multiply by 1000000. So 1 km = 1.00000e+6 mm.
When would I need to convert millimetre to kilometre?
Length conversions appear in piping, layout, and mechanical drawings — particularly when reconciling imperial fittings or instrument lengths with metric plant drawings.
Is the conversion exact?
Yes. Both mm and km are defined by exact SI relationships, so the displayed factor is exact (any rounding shown is only for display).