Speed Converter

Convert any speed unit

This converter handles meters per second, kilometers per hour, miles per hour, feet per second, knots and even Mach (relative to the speed of sound at sea level). It is ideal for driving, running, aviation, sailing and physics problems.

Conversions are exact (1 mph = 0.44704 m/s, 1 knot = 1 nautical mile per hour), and swapping units recalculates everything instantly.

Popular speed conversions

• km/h to mph and mph to km/h
• m/s to km/h for physics
• Knots to mph for sailing and aviation

Key features at a glance

• Converts km/h, mph, m/s, feet per second, and knots
• Includes Mach, relative to the speed of sound at sea level
• Live conversion table updates as you type
• Exact results based on standard definitions
• Covers driving, running, sailing, aviation, and physics
• Runs entirely in your browser, even offline

Speed as distance over time

Every speed unit is simply a distance divided by a time, which is why there are so many of them — any length unit paired with any time unit gives a measure of speed. Kilometers per hour and miles per hour pair a distance with an hour for everyday travel, meters per second uses SI base units for physics, and feet per second appears in ballistics and engineering.

Because they all share the same underlying structure, converting between them is exact and consistent. One mile per hour is precisely 0.44704 meters per second, derived from the exact definitions of the mile and the second. The converter applies these fixed ratios, so a car's speed in km/h, a sprinter's pace in m/s, and a wind speed in mph all translate cleanly into one another.

Knots, nautical miles, and Mach

Some speed units carry history and specialized meaning. The knot — one nautical mile per hour — is the standard for ships and aircraft because the nautical mile is tied to the Earth's geometry, making navigation calculations natural. The name itself comes from the old practice of measuring a ship's speed by counting knots in a rope let out behind it over a fixed time.

Mach number is different again: it expresses speed as a fraction of the speed of sound, so Mach 1 is the sound barrier. Because the speed of sound varies with air temperature and altitude, this converter uses the standard sea-level value as a reference. Mach is essential in aviation, where the aerodynamic behavior of an aircraft depends on its speed relative to sound rather than an absolute figure.

Pace versus speed

Runners and cyclists often think in pace rather than speed — minutes per kilometer or per mile instead of distance per hour. Pace is the reciprocal of speed: a faster runner has a higher speed but a lower (shorter) pace time. The two describe the same motion from opposite directions, which is why a small change in pace can correspond to a meaningful change in speed.

While this converter works in speed units, understanding the relationship helps you interpret results. If you know your pace, you can convert it to a speed and then into any unit here; conversely, a speed in km/h can be turned back into a per-kilometer pace. Keeping the inverse relationship in mind avoids the common confusion of treating faster and slower the wrong way around.

Tips for converting speed

• Remember 1 mph is about 1.609 km/h for quick driving conversions
• Multiply m/s by 3.6 to get km/h
• Use knots for sailing and aviation, not statute mph
• Mach depends on altitude and temperature — sea level is the reference here
• Pace (time per distance) is the inverse of speed (distance per time)

Why choose our speed converter?

Our converter is completely free with no signup, no limits, and no subscription. It runs entirely in your browser, so conversions are instant, it works offline, and the values you enter never leave your device.

It is one of more than 200 free tools on ToopTools, and you can pin it to your My Workspace, a personalized workspace where you keep the tools you use most in a single dashboard. Beside the other unit converters, it covers every speed conversion from walking pace to Mach in one place.

Common use cases

Drivers use the speed converter when a foreign speed limit is posted in unfamiliar units, runners and cyclists convert their pace data between metric and imperial, and sailors and pilots work in knots. It puts every common speed unit on the same footing instantly.

Students use it for physics problems involving meters per second, aviation enthusiasts use Mach, and anyone comparing vehicle specs from different countries uses it to translate top speeds. Because it shows a full table, you read a speed in every unit at once without converting one at a time.

Is the speed converter free?

Yes. It is completely free with no account, no sign-up, and no usage limits. Convert as many speeds as you like at no cost.

How do I convert km/h to mph?

Multiply the km/h value by about 0.621371 to get mph, or just enter it in the converter. As a rough guide, 100 km/h is about 62 mph, useful for reading speed limits abroad.

What is a knot?

A knot is one nautical mile per hour, about 1.852 km/h or 1.151 mph. It is the standard speed unit for ships and aircraft because the nautical mile is based on the Earth's geometry.

What does Mach 1 mean?

Mach 1 is the speed of sound. Because the speed of sound changes with air temperature and altitude, this converter uses the standard sea-level value of roughly 1,225 km/h as the reference for Mach numbers.

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

Multiply meters per second by 3.6 to get kilometers per hour, since there are 3,600 seconds in an hour and 1,000 meters in a kilometer. The converter does this exactly for you.

Are my conversions kept private?

Yes. Everything is computed in your browser and nothing is uploaded, so the values you enter stay private and the tool works without an internet connection.

How do I convert mph to km/h?

Enter the speed in miles per hour and choose kilometers per hour as the target, and the converter shows the result instantly. It also supports m/s, knots, feet per second, and Mach, so you can switch between everyday and technical speed units easily.

Does the speed converter work offline?

Yes. The conversion runs entirely in your browser, so once the page has loaded the tool works without an internet connection, and nothing you enter is uploaded — it stays private on your own device.