Speed Converter
Convert mph to km/h, km/h to mph, knots, m/s and feet per second instantly.
This speed converter changes any velocity into another unit as soon as you type. It covers the conversions drivers, runners, sailors and pilots reach for most — mph to km/h across borders, m/s in physics class, and knots at sea or in the air.
About the speed converter
Speed measures how much distance is covered in a unit of time. Road speeds are shown in miles per hour (mph) in the US and UK and in kilometres per hour (km/h) across most of the world, so converting between them is essential when driving abroad or reading imported specifications. Scientists use metres per second (m/s), the SI unit, while ships and aircraft measure speed in knots (nautical miles per hour).
Each value here is anchored to the metre per second. One km/h equals exactly 1000⁄3600 m/s, one mph equals 0.44704 m/s, and one knot equals 1852⁄3600 m/s (0.514444 m/s). Because these definitions are exact, the converter gives precise results — for example, a 100 km/h limit is exactly 62.14 mph, and a 60 mph highway speed is 96.56 km/h.
How to use this speed converter
- Enter the speed you want to convert in the value box.
- Pick the unit you are converting from (for example, miles per hour).
- Pick the unit you want the result in (for example, kilometres per hour).
- The converted speed updates instantly as you type.
- Use the swap arrows to reverse direction, or view the grid to see every speed unit together.
Speed conversion factors
Exact reference factors used by this converter:
Supported speed units
- km/hKilometre / hour
- mphMile / hour
- m/sMetre / second
- ft/sFoot / second
- knKnot
Frequently asked questions
How do I convert mph to km/h?
Multiply miles per hour by 1.609344. For example, 60 mph × 1.609344 = 96.56 km/h. To convert km/h to mph, multiply by 0.621371.
How fast is 100 km/h in mph?
100 km/h equals about 62.14 mph. This is a common motorway/highway speed, so it is one of the most-searched speed conversions.
What is a knot?
A knot is one nautical mile per hour, used in shipping and aviation. One knot equals 1.852 km/h or about 1.151 mph. It comes from an old method of measuring speed with knotted rope.
How do I convert m/s to km/h?
Multiply metres per second by 3.6. So 10 m/s = 36 km/h. To go from km/h to m/s, divide by 3.6.
Which speed unit does science use?
The metre per second (m/s) is the SI unit of speed and is standard in physics. This converter treats m/s as its base unit, so all other units are defined precisely against it.