Speed Converter
km/h, mph, m/s and knots.
Convert Speeds Between km/h, mph, m/s, and Knots
Whether you're comparing your car's top speed, analyzing weather data, or reading a pilot's report, you'll often need to convert between units of speed. This tool handles the five most common: meters per second (m/s), kilometers per hour (km/h), miles per hour (mph), feet per second (ft/s), and knots (nautical miles per hour).
Quick Conversion Reference
- 1 km/h = 0.621371 mph = 0.277778 m/s
- 1 mph = 1.609344 km/h = 0.44704 m/s
- 1 m/s = 3.6 km/h = 2.237 mph
- 1 knot = 1.852 km/h = 1.15078 mph
Where Each Unit Is Used
Kilometers per hour (km/h) is the standard unit for road speed in most of the world. Miles per hour (mph) is used in the United States and the United Kingdom. Meters per second (m/s) is the SI unit, preferred in physics and engineering. Feet per second (ft/s) is common in American engineering and projectile calculations. Knots are used in aviation and maritime navigation, because they're defined by the nautical mile — one minute of arc along the Earth's meridian.
Tips for Mental Conversion
For a rough mph ↔ km/h conversion on the fly, multiply mph by 1.6 or divide km/h by 1.6. For a slightly more accurate estimate, multiply mph by 1.6 and add 10% (since 1.6 × 1.1 ≈ 1.76, close enough to 1.6 that the adjustment is small). For m/s from km/h, divide by 3.6. For knots from mph, multiply by about 0.87.