Speed Converter

Convert speed between kilometers per hour, miles per hour, meters per second, knots, feet per second and Mach — free, instant and private. Every conversion is calculated right in your browser.

How to use the speed converter

  1. Enter a value. Type the speed you want to convert into the Value box — for example, 100 to convert 100 km/h.
  2. Choose your units. Pick the unit to convert from and the unit to convert to. Use the ⇄ button to swap them in one click.
  3. Read the result. The converted speed appears instantly, together with a full table showing the same value in every other speed unit.

About this tool

This free speed converter turns any velocity into another unit in real time. It is handy for drivers comparing km/h and mph when travelling abroad, runners and cyclists checking their pace, sailors and pilots working in knots, and physics students who need meters per second. The knot is defined as one nautical mile per hour, and Mach expresses speed relative to the speed of sound (about 340.29 m/s at sea level), so the tool covers everything from a walking pace to supersonic flight.

All conversions use precise, internationally agreed factors — 1 mile per hour equals exactly 0.44704 m/s and 1 knot equals exactly 0.514444 m/s — so the numbers match official figures. Because the math runs entirely in your browser with JavaScript, nothing you type is uploaded or stored, and the converter keeps working even if you go offline after the page has loaded.

Frequently asked questions

How many mph is 100 km/h?

100 kilometers per hour is about 62.14 miles per hour. To convert km/h to mph, divide by 1.609344; to go the other way, multiply mph by 1.609344.

How do I convert m/s to km/h?

Multiply meters per second by 3.6 to get kilometers per hour. For example, 10 m/s equals 36 km/h. To convert km/h back to m/s, divide by 3.6.

What is a knot?

A knot is one nautical mile per hour, used in aviation and at sea. One knot equals 1.852 km/h or roughly 1.151 mph, because a nautical mile is 1,852 meters.

What speed is Mach 1?

Mach 1 is the speed of sound. This tool uses the sea-level value of about 340.29 m/s (1,225 km/h or 761 mph). The true speed of sound falls as air gets colder, so Mach 1 is slower at high altitude.