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Speed Converter

Speed conversion is needed for navigation (knots to mph/km/h), physics (m/s to km/h), and travel planning. Our converter handles all common speed units including running pace (min/mile, min/km) which requires inverse conversion — slower runners have higher pace numbers, opposite to speed.

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About the Speed Converter

Speed conversion is needed for navigation (knots to mph/km/h), physics (m/s to km/h), and travel planning. Our converter handles all common speed units including running pace (min/mile, min/km) which requires inverse conversion — slower runners have higher pace numbers, opposite to speed.

How to use it

  1. Enter a speed value and select the unit: mph, km/h, m/s, knots, fps, Mach.
  2. See instant conversions across all speed units.
  3. Use the running pace converter: enter mph or km/h to get minutes per mile/km.
  4. Use the light speed converter for astronomy and physics.

Formula & methodology

1 mph = 1.60934 km/h = 0.44704 m/s = 0.86898 knots. 1 knot = 1.15078 mph = 1.852 km/h (1 nautical mile/hour). 1 Mach ≈ 340.3 m/s at sea level (varies with altitude and temperature). Running pace (min/km) = 60 / speed (km/h). Speed of light: 299,792,458 m/s.

Common use cases

  • Aviation: converting between knots (airspeed) and km/h or mph
  • Running: converting training pace between miles and kilometers
  • Weather: wind speed in knots, mph, km/h, or Beaufort scale
  • Physics: expressing velocities in m/s for equations
  • International driving: speed limits in km/h when used to mph

Frequently asked questions

One knot = one nautical mile per hour. A nautical mile is exactly 1/60 of a degree of latitude (1,852 meters). This means navigators can directly read distance from latitude on charts without conversion. A ship traveling at 20 knots on a heading covers 20 nautical miles per hour — directly readable on navigation charts. It simplifies celestial navigation.
Mach 1 is the local speed of sound, which varies with air temperature and density. At sea level (15°C): ~340 m/s (761 mph). At 35,000 ft (cruise altitude, −56°C): ~295 m/s (660 mph). Supersonic aircraft are rated in Mach rather than mph because the aerodynamic effects depend on the ratio to local sound speed, not absolute velocity.

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