Velocity
km/htomm/s
Convert kilometres per hour (km/h) to millimetres per second (mm/s).
Factor1 km/h = 277.7778 mm/s
Converter
km/h
Accepts numbers or expressions, e.g. 150 + 14.7
Result
mm/s
Rendered to 6 significant figures.
Formula
Formula
mm/s = km/h × 277.7778
Multiply any value in kilometres per hour by 277.7778 to obtain the value in millimetres per second.
Worked example
Convert 1 km/h to mm/s.
- 01Start with 1 km/h.
- 02Multiply by the conversion factor: 1 × 277.7778 = 277.778 mm/s.
Result1 km/h = 277.778 mm/s
Conversion table
| km/h | mm/s |
|---|---|
| 1 | 277.78 |
| 2 | 555.56 |
| 5 | 1388.9 |
| 10 | 2777.8 |
| 20 | 5555.6 |
| 50 | 13889 |
| 100 | 27778 |
| 200 | 55556 |
| 500 | 1.3889e+5 |
| 1000 | 2.7778e+5 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from km/h to mm/s?
1 km/h equals 277.7778 mm/s. To convert, multiply the value in kilometres per hour by 277.7778.
How do I convert 1 km/h to mm/s?
1 km/h = 277.778 mm/s. For any value, multiply by 277.7778.
How do I convert mm/s back to km/h?
Divide by the same factor — or equivalently, multiply by 0.0036. So 1 mm/s = 0.0036 km/h.
When would I need to convert kilometre per hour to millimetre per second?
Velocity conversions are needed for fluid flow analysis (line velocity targets, erosional limits), gas-stream calculations, and equipment specs that mix m/s, ft/s and engineering speed units.
Is the conversion exact?
The factor shown is precise to at least 7 significant figures. For most process-engineering work this is far better than instrument accuracy. For metrology or trade applications, refer to the relevant national standard (NIST, BIPM, ISO 80000).