Speed Converter
Convert km/h, mph, m/s, knots, and more.
- kmh
- mph
- knots
- speed
- velocity
About Speed Converter
Speed shows up in different units depending on the domain. Cars and weather forecasts use km/h or mph. Sailing and aviation use knots (nautical miles per hour). Physics and engineering favour metres per second. Runners think in minutes per kilometre or mile. Each domain treats its own unit as the natural one, which makes cross-domain conversions awkward without a calculator.
This converter handles the common speed units side by side, with exact conversion factors (1 mph = 1.609344 km/h, 1 knot = 1.852 km/h). Enter a value once and see it expressed in every unit at once.
How to use
Type a speed into the input and pick its unit from the dropdown — kilometres per hour, miles per hour, metres per second, knots, feet per second, and more. The conversions panel below shows the value in every other unit, each with a copy button.
Tap any row in the conversions list to make that unit the new input — handy for "60 mph in knots? OK, now what's that in m/s?" without retyping. The URL updates with the current value and unit so you can bookmark a specific conversion.
Frequently asked questions
How fast is one knot in km/h or mph?
One knot is exactly 1.852 km/h, or about 1.1508 mph. So a ship cruising at 20 knots is doing 37 km/h or 23 mph — slower than most people expect, but standard for cargo and cruise vessels.
Why does aviation use knots instead of km/h?
Because one knot equals one nautical mile per hour, and the nautical mile is defined as one minute of arc of latitude. That makes navigation maths trivial when reading off a chart: a heading and a knot speed translate directly into degrees of arc covered per hour, without unit conversions.
What's the conversion between km/h and m/s?
Divide km/h by 3.6 to get m/s, or multiply m/s by 3.6 to get km/h. So 100 km/h is 27.78 m/s, and 10 m/s is 36 km/h — useful for sanity-checking physics problems against everyday driving experience.
How fast is the speed of sound?
In dry air at 20 °C (sea level), about 343 m/s, 1,235 km/h, 767 mph, or 667 knots — known as Mach 1. The speed depends on the air temperature (warmer air = faster sound) and slightly on humidity, but the sea-level figure is the standard reference for aircraft performance.