Speed

About Speed Conversion

Speed measures how fast an object moves over a given distance in a specific time. It's crucial for driving, aviation, maritime navigation, athletics, meteorology, and scientific calculations. Understanding speed conversions helps you interpret speed limits when traveling abroad, compare vehicle performance, or work with data from different sources.

Different regions and industries use different speed units: kilometers per hour (km/h) in most countries, miles per hour (mph) in the US and UK, knots in aviation and maritime contexts, and meters per second (m/s) in physics and engineering. Weather services often report wind speeds in different units depending on the country.

Our speed converter handles all common units for everyday use and specialized applications, from highway driving to supersonic aircraft and space travel calculations.

Common Speed Conversions

Speed Unit Reference

Meters per Second (m/s) – The SI unit of speed used in physics, engineering, and scientific research. 1 m/s = 3.6 km/h. Used for precise calculations and as the base for derived units.

Kilometers per Hour (km/h) – Standard speed unit in most countries for vehicles and weather reports. Used on road signs throughout Europe, Asia, Australia, and South America. Easy to relate to distances in kilometers.

Miles per Hour (mph) – Used in the US, UK, and their territories for vehicle speeds and speed limits. 60 mph ≈ 97 km/h. Also common in some Caribbean and African countries with historical British influence.

Knot (kn) – Nautical and aviation speed unit equal to 1 nautical mile per hour (1.852 km/h). Named for the knots tied in a ship's log line used to measure speed. Used because nautical miles relate directly to latitude—1 nautical mile = 1 minute of latitude.

Feet per Second (ft/s) – Common in US engineering, ballistics, and some sports contexts. 1 ft/s = 0.3048 m/s ≈ 0.68 mph. Used for bullet velocities and some industrial applications.

Mach Number – Ratio of speed to the local speed of sound. Mach 1 = speed of sound, approximately 343 m/s (1,235 km/h) at sea level and 20°C. Varies with temperature and altitude. Aircraft exceeding Mach 1 are supersonic; above Mach 5 is hypersonic.

Speed of Light (c) – The cosmic speed limit: exactly 299,792,458 m/s. Used in physics and astronomy for relativistic calculations. Light travels about 9.46 trillion kilometers per year (one light-year).

Learn More

Explore our in-depth guides on this topic:

• MPH vs KM/H: Understanding Speed Units
• How to Convert Knots to MPH and KM/H
• Running Speeds and Pace Conversion