FreeToolStation

Speed Converter

km/h, mph, m/s, knots and Mach.

Unit Converters Free, no sign-up Runs in your browser
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Result
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To twelve digits
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Conversion factor
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The other way
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In scientific notation
UnitValueSymbol
Minutes per kilometre is a pace rather than a speed -- it goes down as you go faster -- so it is listed in the table but not used as a conversion source. The running pace calculator handles pace properly.

About the Speed Converter

Speed Converter covers the units speed is quoted in across road, air, sea and science: kilometres per hour, miles per hour, metres per second, knots, feet per second and Mach.

A knot is one nautical mile per hour, which is 1.852 km/h exactly, and it is used at sea and in the air because it relates directly to latitude: one knot for one hour covers one minute of arc. Treating a knot as a mile per hour understates a speed by about fifteen per cent.

Metres per second is the scientific unit and the one physics formulas expect, which is why converting into it is usually the first step in any calculation. The handy approximation is that km/h divided by 3.6 gives m/s, and that factor is exact rather than rounded.

The page shows its working, not just its answer. Where there is a formula it is printed with your own numbers substituted in, so you can check the result rather than take it on trust -- which is the difference between a calculator you can use for something that matters and one you cannot.

Everything runs inside your browser. What you type is never uploaded, never logged and never stored, and the calculator keeps working if your connection drops after the page has loaded.

Looking for something this does not cover? FreeToolsHub.org is another hub of free online tools that need no account, and it is worth a look if speed converter is only part of what you are working on.

How to use the Speed Converter

  1. Choose from and toThe fields below change to match what you pick, so only the figures that matter to your case are asked for.
  2. Enter valueDecimals are fine, and thousands separators are accepted and ignored.
  3. Read the result, to twelve digits and conversion factorThe figures update as you type. The Calculate button is there if you would rather press something, but nothing waits for it.
  4. Copy or check the resultCopy the summary with the copy button, or open the table to check it row by row.

Features

  • Shows result, to twelve digits, conversion factor, the other way and in scientific notation together, so you are not running it twice
  • A results table you can read across
  • Updates as you type, with no button to press and no page reload
  • Copy the result in one click
  • Free, no sign-up, and it runs entirely in your browser

Who uses this tool

The speed converter is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

  • Converting a speed limit between km/h and mph
  • Turning a wind speed in knots into km/h
  • Converting to metres per second for a physics problem
  • Comparing a running speed with a cycling one

Frequently asked questions

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

Divide by 3.6. The factor is exact, since an hour is 3,600 seconds and a kilometre is 1,000 metres.

What is a knot?

One nautical mile per hour, exactly 1.852 km/h. It is used in aviation and at sea because it corresponds to one minute of latitude per hour.

Is Mach a fixed speed?

No. It is the ratio to the local speed of sound, which falls with temperature and so with altitude. The figure here uses the sea-level value of 340.29 m/s.

If the speed converter is not quite what you need, these other free tools solve closely related problems, and there are 18 more in unit converters.

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Checked and rebuilt on 2026-10-14. The method this calculator uses is described in the section above, and corrections go through the contact page.