Convert speed units like MPH, KPH, Knots, and Mach.
Instantly convert between different units of speed with our comprehensive Speed Converter. Whether you're a driver comparing speed limits, a pilot calculating flight velocity, or a student working on physics problems, this tool makes unit conversion effortless. Support is included for Miles per Hour (mph), Kilometers per Hour (kph), Knots, Mach, and Meters per Second (m/s).
Convert simultaneously between 5 major speed units used in automotive, aviation, and science.
Get accurate results with up to 4 decimal places for scientific and technical requirements.
No need to press a button; values update automatically as you type or change units.
| Unit | Abbreviation | Primary Usage |
|---|---|---|
| Miles per Hour | mph | Road traffic in US, UK |
| Kilometers per Hour | kph / km/h | Road traffic worldwide (except US, UK) |
| Knots | kn | Maritime and Aviation |
| Meters per Second | m/s | Scientific (SI Unit), Physics |
| Mach | M | High-speed flight (relative to speed of sound) |
Converting speed limits when driving in a different country (e.g., US driver in Europe).
Comparing athlete speeds, pitch speeds, or race times across different metric systems.
Translating knots to land-based units for easier visualization.
Helping students verify homework answers for unit conversion problems.
The speed of sound varies by temperature and medium. In dry air at 20°C (68°F), it is approximately 343 meters per second, 1235 kph, or 767 mph.
Knots are based on the nautical mile, which corresponds to one minute of latitude on the Earth's surface. This makes it convenient for navigation charts.
A rough approximation is to divide by 1.6. A simpler trick: divide by 2 and add 10% (e.g., 100 kph / 2 = 50 + 5 = 55 mph). The actual value is 62 mph, but it gets you close!