Speed Unit Converter

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Speed Conversion for All Needs

Convert between all common speed and velocity units with our precise converter. Easily transform between kilometers per hour, miles per hour, meters per second, knots, and more specialized units including the speed of light and sound.

Common Speed Conversions

  • 1 kilometer per hour (km/h) = 0.621371192 miles per hour
  • 1 mile per hour (mph) = 1.609344 kilometers per hour (exact)
  • 1 meter per second (m/s) = 3.6 kilometers per hour (exact)
  • 1 knot = 1.852 kilometers per hour (exact)
  • 1 foot per second (ft/s) = 0.3048 meters per second (exact)

Speed Units and Standards

Speed is measured as distance divided by time:

  • Meter per second (m/s): SI derived unit
  • Kilometer per hour (km/h): Common in everyday use
  • Mile per hour (mph): Standard in US and UK
  • Knot: Used in navigation (1 nautical mile per hour)

Understanding Speed Measurements

Speed measures the rate of change in position with respect to time. It's a scalar quantity representing how fast something moves, regardless of direction. Velocity, by contrast, is a vector quantity that includes both speed and direction. In everyday usage, speed and velocity are often used interchangeably.

Precision: 15 decimal places
Standard: ISO 80000-3:2019

Reference Speeds

Natural and Physics Reference Speeds

  • Speed of light in vacuum: 299,792,458 m/s (exact)
  • Speed of sound in air (sea level, 20°C): 343 m/s
  • Escape velocity from Earth: 11.186 km/s
  • Earth's orbital speed around Sun: 29.78 km/s

Transportation Reference Speeds

  • Average walking pace: 5 km/h (3.1 mph)
  • Typical highway speed limit: 100 km/h (62 mph)
  • Commercial jet cruising speed: 900 km/h (560 mph)
  • Sound barrier (Mach 1): 1,235 km/h (767 mph) at sea level

Speed Units in Different Systems

Metric Speed Units

The metric system primarily uses:

  • Meters per second (m/s): SI derived unit
  • Kilometers per hour (km/h): Common for vehicles
  • Centimeters per second (cm/s): Used in some scientific contexts

Imperial/US Speed Units

Imperial and US customary units for speed include:

  • Miles per hour (mph): Common for vehicles
  • Feet per second (ft/s): Used in physics and engineering
  • Inches per second (in/s): Used for some mechanical applications

Specialized Speed Units

Some fields use specialized speed measurements:

  • Knot: One nautical mile per hour (used in aviation and marine navigation)
  • Mach: Ratio of object's speed to the speed of sound (aviation)
  • c: Used in physics where c=1 is the speed of light