- Enter Speed — Type any numeric speed value into the input field.
- Select Units — Choose source and target units from 8 speed units: cm/s, m/s, km/h, mph, ft/s, knots, Mach, and speed of light. Use the swap button to reverse.
- See Results — Real-time conversion with all other equivalents shown simultaneously.
- Copy Result — Click 'Copy' to copy the converted value.
Speed Converter — Instant Velocity Unit Conversion
The Speed Converter is a free, instant-use tool that converts between 8 velocity units covering everyday, maritime, aviation, and scientific applications. Whether you're converting car speeds between km/h and mph, calculating aircraft speeds in knots or Mach numbers, or working with physics problems involving meters per second, this tool provides accurate real-time conversions.
All calculations are performed entirely in your browser using exact conversion factors. No data is sent to any server, making this tool suitable for professional, educational, and personal use.
Supported Speed Units
- Centimeters per second (cm/s) — Used in scientific experiments, fluid dynamics, and precision measurements where small velocities need to be expressed precisely.
- Meters per second (m/s) — The SI unit of speed. Used in physics, engineering, and scientific contexts worldwide. The fundamental unit from which others are derived.
- Kilometers per hour (km/h) — The most widely used speed unit globally for road vehicles, speed limits, and weather reports. Used in all metric countries.
- Miles per hour (mph) — The primary speed unit in the United States and United Kingdom for road vehicles and speed limits.
- Feet per second (ft/s) — Used in some engineering applications, ballistics, and the imperial measurement system. Common in the US for projectile speeds.
- Knots (kn) — One nautical mile per hour (1.852 km/h). The international standard for maritime and aviation speeds worldwide. Used by ships, aircraft, and weather services.
- Mach — The ratio of speed to the speed of sound (approximately 343 m/s at standard sea-level conditions). Mach 1 = speed of sound, used extensively in aviation and aerospace for describing aircraft speeds.
- Speed of Light (c) — 299,792,458 m/s exactly. The maximum speed in the universe, used in physics, astronomy, and relativistic calculations. One light-year is the distance light travels in one year.
Key Conversion Factors
- 1 km/h = 0.27778 m/s = 0.62137 mph
- 1 mph = 1.60934 km/h = 0.44704 m/s
- 1 knot = 1.852 km/h = 1.15078 mph
- Mach 1 ≈ 343 m/s = 1,235 km/h = 767 mph
- Speed of light = 299,792,458 m/s ≈ 1.079 billion km/h
Key Features
- Real-Time Conversion — Results update instantly as you type.
- All-Unit View — Enter any speed and see all 7 other unit equivalents simultaneously.
- Swap Button — Reverse conversion direction with one click.
- Scientific Notation — Very large or small numbers display in scientific notation.
- Copy to Clipboard — Copy results instantly.
Common Use Cases
- Travel — Convert speed limits between km/h and mph when driving in different countries.
- Aviation — Convert between knots, km/h, and Mach numbers for flight planning and air traffic control.
- Maritime — Convert ship speeds between knots and km/h or mph for navigation.
- Weather — Convert wind speeds between different units used by weather services worldwide.
- Sports — Convert athletic speeds (running, cycling, swimming) between metric and imperial units.
- Physics Education — Convert between SI units (m/s) and practical units (km/h, mph) for problem solving.
Privacy and Browser Support
All conversions run entirely in your browser. No data is transmitted to any server. Works in all modern browsers including Chrome, Firefox, Edge, Safari, and mobile browsers. No internet connection required after initial page load.