🚀 Unit Converter
Speed Converter
Convert between m/s, km/h, mph, knots, ft/s, Mach, and speed of light — all results shown at once.
Common Speed Reference Points
| Activity / Object | m/s | km/h | mph |
|---|---|---|---|
| Walking | 1.4 m/s | 5 km/h | 3.1 mph |
| Cycling | 5.5 m/s | 20 km/h | 12.4 mph |
| Car (Highway) | 30 m/s | 108 km/h | 67 mph |
| High-Speed Train | 83 m/s | 300 km/h | 186 mph |
| Commercial Airplane | 240 m/s | 864 km/h | 537 mph |
| Speed of Sound (Mach 1) | 343 m/s | 1,235 km/h | 767 mph |
| Speed of Light (c) | 299,792,458 m/s | 1.079 × 10⁹ km/h | 6.706 × 10⁸ mph |
Frequently Asked Questions
What is Mach speed?
Mach is a dimensionless quantity representing the ratio of an object's speed to the speed of sound in the surrounding medium. Mach 1 equals the speed of sound, which is approximately 343 m/s (1,235 km/h or 767 mph) at sea level at 20°C. Mach 2 is twice the speed of sound, Mach 3 is three times, and so on. Fighter jets and supersonic aircraft are typically described using Mach numbers.
What is the difference between knots and mph?
A knot is one nautical mile per hour, while mph is one statute (land) mile per hour. One nautical mile equals 1,852 meters, while one statute mile equals 1,609.344 meters. Therefore, 1 knot equals approximately 1.15078 mph. Knots are primarily used in aviation and maritime navigation, while mph is used for road speeds in the US and UK.
How fast is the speed of light?
The speed of light in a vacuum is exactly 299,792,458 meters per second (approximately 3 × 10⁸ m/s). This equals about 1,079,252,849 km/h or 670,616,629 mph. The speed of light is a fundamental constant of nature and represents the maximum speed at which all energy, matter, and information can travel.
How do you convert km/h to m/s?
To convert kilometers per hour to meters per second, divide the km/h value by 3.6. For example, 100 km/h ÷ 3.6 ≈ 27.78 m/s. This works because 1 km equals 1,000 meters and 1 hour equals 3,600 seconds, so the conversion factor is 1000/3600 = 1/3.6.
What is a typical walking speed?
A typical adult walking speed is about 1.4 m/s, which equals approximately 5 km/h or 3.1 mph. Cycling speed averages around 5.5 m/s (20 km/h or 12.4 mph). Highway driving in most countries ranges from 27-36 m/s (100-130 km/h or 62-81 mph). Commercial airplanes cruise at about 240 m/s (864 km/h or 537 mph).