Speed Converter

Convert between different speed units - km/h, mph, m/s, knots, and more

Speed

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What Is Speed Conversion?

Speed is a measure of how fast an object is moving. It is defined as the distance covered per unit of time. Because different countries and industries use different units of measurement, converting speed from one unit to another is a common requirement.

For example, while the United States uses Miles per Hour (mph) for road speeds, most other countries use Kilometers per Hour (km/h). Aviation and marine industries often use Knots.

Common Units of Speed

Here are the units supported by this converter and where they are commonly used:

Kilometers per Hour (km/h): The SI derived unit of speed, used on road signs and speedometers in most countries.
Miles per Hour (mph): Used on road signs and speedometers in the United States and the United Kingdom.
Meters per Second (m/s): The SI base unit of speed, commonly used in physics and scientific calculations.
Knots (kn): A unit of speed equal to one nautical mile per hour, used in aviation and maritime navigation.
Feet per Second (ft/s): A unit of speed used in engineering and ballistics in the US.

How to Convert Speed Units?

Our converter handles all the math for you, but here are some common conversion factors if you want to calculate manually:

From km/h to mph: Multiply by 0.621371
From mph to km/h: Multiply by 1.60934
From m/s to km/h: Multiply by 3.6
From knots to mph: Multiply by 1.15078

Frequently Asked Questions (FAQs)

What is the fastest speed possible?

According to the theory of relativity, the speed of light in a vacuum is the absolute speed limit for all energy and matter in the universe. It is approximately 299,792,458 meters per second (about 1.079 billion km/h!).

Why do ships and airplanes use knots?

A knot is based on nautical miles. One nautical mile is equal to one minute of latitude on the Earth's surface. This makes navigation calculations much simpler when using charts.

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

A quick mental trick is to divide the speed in km/h by 3.6 to get meters per second. For example, 36 km/h divided by 3.6 is 10 m/s.