Skip to content

Speed Converter

Convert between metres per second, kilometres per hour, miles per hour, knots and Mach.

Speed Converter

Professional grade conversion for speed units.

Meters per Second
Select Unit
3.599997
Kilometers per Hour
Select Unit

Conversion Formula

1 Meters per Second ≈ 3.599997 Kilometers per Hour

What Speed Converter does

Speed units are tied to the domain that uses them: metres per second in physics, kilometres or miles per hour on roads, knots at sea and in the air.

The knot is one nautical mile per hour, and the nautical mile was originally defined as one minute of latitude, which is why it survives in navigation: it maps directly onto a chart.

  • Metres per second, kilometres per hour, miles per hour
  • Knots for marine and aviation use
  • Mach as a reference speed of sound

How to use Speed Converter

  1. 1

    Enter the value

    Type the amount you want to convert. The result updates as you type.

  2. 2

    Select the units

    Choose what your value is in and what you want it in, for example kilometres per hour to miles per hour.

  3. 3

    Copy the result

    The copy button gives you the unformatted number, without thousands separators, ready to paste into a spreadsheet or code.

Limits and known behaviour

  • Mach is treated as a fixed 343 metres per second, the approximate speed of sound in air at 20 °C at sea level. The real speed of sound falls with temperature, so at cruising altitude Mach 1 is meaningfully slower. Use this as an approximation only.
  • Speed conversions do not account for wind or current, so an air or water speed is not a speed over the ground.
  • Arithmetic uses double-precision floating point, so a converted value can end in a small representation residue. That is a property of binary arithmetic, not of the conversion factor.

Privacy and data handling

Runs entirely in your browser

  • The conversion is arithmetic performed in this page. Nothing you enter is transmitted or stored.
  • The tool works offline once the page has loaded.

Site-wide data handling, including analytics and advertising, is described in the privacy policy.

Frequently asked questions

Why do ships and aircraft use knots?

Because a nautical mile corresponds to one minute of latitude, so a speed in knots translates directly into progress across a chart without a conversion step.

Is Mach 1 always the same speed?

No. The speed of sound depends mainly on air temperature, so it decreases with altitude. The fixed value used here is a sea-level approximation.