Speed Converter
Convert speed units between km/h, mph, m/s, knots, Mach, and ft/s with this free online speed converter. Interactive comparison chart shows every unit side by side for easy reference.
About This Calculator
The Speed Converter is a versatile online tool that allows you to convert speed measurements between multiple unit systems instantly. Whether you need to convert kilometers per hour (km/h) to miles per hour (mph) for road trips, meters per second (m/s) for scientific calculations, knots for maritime and aviation purposes, Mach numbers for aerospace, or feet per second (ft/s) for engineering applications, this converter handles all common speed units. It is designed for students, engineers, pilots, sailors, automotive enthusiasts, scientists, and anyone needing quick and accurate speed conversions.
The converter works by using precise conversion factors between speed units. When you enter a value and select the source and target units, it first converts the input to a base unit (meters per second) using the source unit's conversion factor. It then converts from the base unit to the target unit. All supported units use internationally accepted conversion factors to ensure maximum accuracy. The tool also displays the entered value in all supported units simultaneously, giving you a complete view of how the speed translates across different measurement systems.
Regional Notes
The calculator supports both metric and imperial systems used worldwide. Kilometers per hour (km/h) and meters per second (m/s) are standard in most countries using the metric system, including India and continental Europe. Miles per hour (mph) is primarily used in the United States and the United Kingdom for road speeds. Knots are the standard unit for maritime and aviation speeds globally. Mach is commonly used in aerospace contexts across all regions for describing aircraft and rocket speeds relative to the speed of sound.
Frequently Asked Questions
How does the Speed Converter work?
The Speed Converter uses internationally accepted conversion factors to convert between speed units. Enter a numeric value, select the source unit and the target unit, and click Convert. The calculator first converts your input to a base unit (meters per second) using the source unit's conversion factor, then converts that value to the target unit. It also shows your speed in all supported units for easy comparison.
What speed units are supported?
The Speed Converter supports six major speed units: meters per second (m/s), kilometers per hour (km/h), miles per hour (mph), knots (kn) for maritime and aviation use, feet per second (ft/s) for engineering, and Mach for aerospace and high-speed applications. Together these cover scientific, everyday, nautical, and aviation speed measurement needs.
Is the conversion accurate?
Yes, all conversions use scientifically accepted and internationally recognized conversion factors for maximum accuracy. Each unit is converted through a common base unit (meters per second) using precise conversion ratios such as 1 km/h = 0.277778 m/s, 1 mph = 0.44704 m/s, and 1 knot = 0.514444 m/s. Results are displayed with up to 6 decimal places for high precision.
How do I convert km/h to mph?
To convert kilometers per hour (km/h) to miles per hour (mph), multiply the speed in km/h by the conversion factor 0.621371. For example, 100 km/h is approximately 62.14 mph. Conversely, to convert mph to km/h, multiply the speed in mph by 1.609344. For instance, 60 mph is approximately 96.56 km/h.
What is a knot and where is it used?
A knot is a unit of speed equal to one nautical mile per hour, or approximately 1.151 miles per hour (1.852 km/h). It is the standard unit of speed used in maritime navigation, aviation, and meteorology worldwide. Both nautical charts and aviation instruments measure speed in knots regardless of the country, making it the universal unit for sea and air travel.
What is Mach speed and how is it calculated?
Mach is the ratio of an object's speed to the speed of sound in the surrounding medium. At sea level and 20°C, Mach 1 equals approximately 340.29 m/s (1,225 km/h or 761 mph). Mach numbers are used in aerospace to describe aircraft and rocket speeds, with subsonic (below Mach 1), transonic (around Mach 1), supersonic (Mach 1 to 5), and hypersonic (above Mach 5) classifications.
How do I convert m/s to km/h?
To convert meters per second (m/s) to kilometers per hour (km/h), multiply the speed by 3.6. For example, 10 m/s equals 36 km/h. Conversely, to convert km/h to m/s, divide the speed by 3.6. For instance, 90 km/h equals 25 m/s. This simple conversion works because 1 km/h equals 0.277778 m/s, and the factor is derived from 1 km = 1000 m and 1 hour = 3600 seconds.