Convert speed units — km/h, mph, m/s, knots, Mach.
| Unit | Name | Value |
|---|---|---|
| m/s | Meter per Second | 0.277778 |
| mph | Mile per Hour | 0.62137169 |
| ft/s | Foot per Second | 0.91134514 |
| kn | Knot | 0.5399577 |
| Mach | Mach | 0.00081629786 |
Common kilometer per hour values converted to foot per second — factor: 1 km/h = 0.9113 ft/s
| Kilometer per Hour (km/h) | Foot per Second (ft/s) | Context |
|---|---|---|
| 5 km/h | 4.557 ft/s | Slow walk |
| 10 km/h | 9.113 ft/s | Fast walk |
| 15 km/h | 13.67 ft/s | Slow cycle |
| 30 km/h | 27.34 ft/s | Fast cycle |
| 50 km/h | 45.57 ft/s | City road |
| 60 km/h | 54.68 ft/s | City road |
| 80 km/h | 72.91 ft/s | Rural road |
| 100 km/h | 91.13 ft/s | Motorway |
| 120 km/h | 109.4 ft/s | Fast motorway |
| 140 km/h | 127.6 ft/s | Fast motorway |
| 200 km/h | 182.3 ft/s | Sports car |
| 300 km/h | 273.4 ft/s | High-speed train |
| 500 km/h | 455.7 ft/s | Propeller plane |
| 900 km/h | 820.2 ft/s | Jet airliner |
| 1,235 km/h | 1,126 ft/s | Speed of sound |
Converting kilometer per hour to foot per second is essential for drivers, pilots, engineers, and scientists working across different measurement systems. Road speed limits, aviation airspeed, nautical navigation, and physics calculations each use different speed units, making quick and accurate conversion a practical everyday skill.
Key reference points: 5 km/h = 4.557 ft/s and 10 km/h = 9.113 ft/s. At higher speeds, 100 km/h = 91.13 ft/s. For reverse conversion, multiply ft/s values by 1.097 to get back to km/h.
All conversions use the internationally recognized factor of exactly 1 km/h = 0.9113 ft/s. Calculations are performed in IEEE 754 double-precision floating point, giving accuracy to at least 8 significant figures — more than sufficient for any practical application.
Formula: Foot per Second = Kilometer per Hour × 0.91134514
Multiply any kilometer per hour value by 0.91134514 to get foot per second. One kilometer per hour equals 0.91134514 ft/s.
Reverse: Kilometer per Hour = Foot per Second × 1.0972791
km/h × 0.9113 = ft/s. Almost 1:1.
One km/h is slightly less than one ft/s.
ft/s × 1.0973 = km/h.
Designs road speed limits, signage, and safety systems using km/h.
Monitors cornering speeds and stage times in km/h during competitions.
Reports wind speeds and storm movement in km/h for public advisories.
Designs track geometry and safety systems for trains running at 300+ km/h.
Measures athlete running, cycling, and swimming speeds in km/h.
Converts km/h speed limits when driving abroad in metric countries.
Kilometers per hour became the standard road speed unit when France adopted the metric system in the late 18th century. As the metric system spread globally through the 19th and 20th centuries, km/h became the dominant speed unit for road transport, aviation weather, and sports in most of the world.
Today, km/h appears on road signs, vehicle speedometers, and weather reports in over 160 countries. It is the official unit in the European Union, China, India, and most of Asia, Africa, and South America.
Interesting fact: Formula 1 cars reach over 350 km/h, and the land speed record stands at 1,228 km/h — set by the Thrust SSC in 1997, breaking the sound barrier on land.
Feet per second is an Imperial unit of speed equal to exactly 0.3048 m/s. It was in common use in Britain and America from the 17th century, particularly in ballistics and military applications.
ft/s remains the standard in US ballistics: bullet velocities, muzzle speeds, and arrow velocities are universally quoted in feet per second. It also appears in HVAC airflow measurements and some engineering contexts.
Interesting fact: A typical rifle bullet travels at 900-1,200 ft/s (270-370 m/s). The speed of sound at sea level is approximately 1,125 ft/s.