Speed Converter
Convert between km/h, mph, m/s, ft/s, knots, and Mach number.
The Speed Converter converts between all common speed and velocity units. Whether you need to convert driving speeds, wind speeds, or aircraft velocities, this tool covers it all.
Supported Units
- m/s: Meters per second (SI standard)
- km/h: Kilometers per hour (worldwide driving)
- mph: Miles per hour (US/UK driving)
- ft/s: Feet per second
- knots: Nautical miles per hour (aviation/maritime)
- Mach: Speed relative to sound (~343 m/s at sea level)
Key Conversions
1 km/h = 0.6214 mph. 1 m/s = 3.6 km/h. 1 knot = 1.852 km/h = 1.151 mph. Mach 1 = 343 m/s = 1,235 km/h at sea level and 15°C. The Mach number varies with altitude and temperature since the speed of sound changes.
Frequently Asked Questions
How do I convert km/h to mph?
Multiply km/h by 0.6214. For example, 100 km/h = 62.14 mph. A quick estimate: multiply km/h by 0.6.
What is a knot?
A knot equals one nautical mile per hour (1.852 km/h). It is used in aviation and maritime navigation because nautical miles relate directly to latitude degrees.
Is the Mach number constant?
No. Mach 1 equals the local speed of sound, which varies with temperature and altitude. At sea level (15°C), Mach 1 ≈ 343 m/s. At cruise altitude, it is lower (~295 m/s).