Velocity Converter
Convert speed units. Exact factors, a quick reference table and worked examples.
100 km/h = 62.13712 mph
The same value in every unit
| Unit | Symbol | Value |
|---|---|---|
| Meter per second | m/s | 27.77778 |
| Millimeter per second | mm/s | 27 777.78 |
| Kilometer per hour | km/h | 100 |
| Mile per hour | mph | 62.13712 |
| Foot per second | ft/s | 91.13444 |
| Inch per second | in/s | 1 093.613 |
| Foot per minute | ft/min | 5 468.066 |
| Knot | kn | 53.99568 |
How to convert velocity units
Every velocity unit is related to one base unit (Meter per second, m/s) by an exact factor. To convert, multiply by the factor of the unit you start from and divide by the factor of the unit you want.
value in new unit = value × (factor of old unit ÷ factor of new unit)
For example, 1 km/h = 0.2777778 m/s and 1 mph = 0.44704 m/s, so 1 km/h = 0.6213712 mph.
Quick reference table
How many of the units in the column headings make up one of the unit in each row.
| One… | = m/s | = mm/s | = km/h | = mph | = ft/s | = in/s |
|---|---|---|---|---|---|---|
| 1 m/s | 1 | 1 000 | 3.6 | 2.236936 | 3.28084 | 39.37008 |
| 1 mm/s | 0.001 | 1 | 0.0036 | 0.002236936 | 0.00328084 | 0.03937008 |
| 1 km/h | 0.2777778 | 277.7778 | 1 | 0.6213712 | 0.9113444 | 10.93613 |
| 1 mph | 0.44704 | 447.04 | 1.609344 | 1 | 1.466667 | 17.6 |
| 1 ft/s | 0.3048 | 304.8 | 1.09728 | 0.6818182 | 1 | 12 |
| 1 in/s | 0.0254 | 25.4 | 0.09144 | 0.05681818 | 0.08333333 | 1 |
| 1 ft/min | 0.00508 | 5.08 | 0.018288 | 0.01136364 | 0.01666667 | 0.2 |
| 1 kn | 0.5144444 | 514.4444 | 1.852 | 1.150779 | 1.68781 | 20.25372 |
Common values: km/h to mph
| Kilometer per hour (km/h) | Mile per hour (mph) |
|---|---|
| 1 km/h | 0.6213712 mph |
| 2 km/h | 1.242742 mph |
| 5 km/h | 3.106856 mph |
| 10 km/h | 6.213712 mph |
| 20 km/h | 12.42742 mph |
| 50 km/h | 31.06856 mph |
| 100 km/h | 62.13712 mph |
| 200 km/h | 124.2742 mph |
| 500 km/h | 310.6856 mph |
| 1 000 km/h | 621.3712 mph |
Worked examples
Convert 100 km/h to mph
- 1 km/h = 0.2777778 m/s and 1 mph = 0.44704 m/s.
- 100 × 0.2777778 ÷ 0.44704 = 62.13712 mph.
Convert 50 km/h to m/s
- 1 km/h = 0.2777778 m/s and 1 m/s = 1 m/s.
- 50 × 0.2777778 ÷ 1 = 13.88889 m/s.
Convert 250 kn to mm/s
- 1 kn = 0.5144444 m/s and 1 mm/s = 0.001 m/s.
- 250 × 0.5144444 ÷ 0.001 = 128 611.1 mm/s.
The units explained
| Unit | Symbol | Exact factor | Where it is used |
|---|---|---|---|
| Meter per second | m/s | 1 m/s = 1 m/s | SI unit |
| Millimeter per second | mm/s | 1 mm/s = 0.001 m/s | Feed rates, vibration |
| Kilometer per hour | km/h | 1 km/h = 0.2777778 m/s | Road vehicles |
| Mile per hour | mph | 1 mph = 0.44704 m/s | US and UK road vehicles |
| Foot per second | ft/s | 1 ft/s = 0.3048 m/s | US flow and ballistics |
| Inch per second | in/s | 1 in/s = 0.0254 m/s | US machine feeds |
| Foot per minute | ft/min | 1 ft/min = 0.00508 m/s | US belts, conveyors, surface speed |
| Knot | kn | 1 kn = 0.5144444 m/s | Ships and aircraft |
Key facts
- v = d ÷ t. 1 m/s = 3.6 km/h = 2.237 mph = 3.281 ft/s.
- Cutting (surface) speed on a rotating tool: v = π × D × n, with D the diameter and n the rotational speed.
- A knot is one nautical mile per hour: 1.852 km/h.
Related converters, guides and tools
- Other converters: Pressure converter, Density converter, Temperature converter, Angles converter, Flow Rate converter, Time converter, Stress converter, Strain converter, Volume converter, Length converter, Mass converter, Force converter, Torque converter, Power converter, Energy converter.
- Guides: Speeds & Feeds.
- Unit Conversions: every converter on one tabbed page that remembers the tabs you use.
- My Dashboard (members): put this converter on your own workspace as a widget beside the others.
FAQ
How many Mile per hour units are in one Kilometer per hour?
1 km/h = 0.6213712 mph.
How do I convert km/h to mph?
Multiply by 0.6213712 (the factor 0.2777778 ÷ 0.44704). To go back, divide by 0.6213712 or multiply by 1.609344.
What is the meter per second (m/s) used for?
SI unit.
What is the millimeter per second (mm/s) used for?
Feed rates, vibration.
Are the conversion factors exact?
Where a unit is defined exactly (the inch is 25.4 mm, the pound is 0.45359237 kg, standard gravity is 9.80665 m/s²) the factor is exact; others are given to ten or more digits. Results are shown to seven significant digits.
References
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI), and NIST Handbook 44, Appendix C (general tables of units of measurement).
- BIPM, The International System of Units (SI Brochure), 9th edition; ISO 80000 (quantities and units).
Last reviewed: November 2026.