This speed conversion calculator enables you to convert between 18 different units of speed measurement in real-time. Choose between popular units, such as kilometers per hour, meters per second, feet per second, miles per hour and knots, or pick some more obscure ones, such as those used in astronomy like kilometers per second or the speed of light. Enter your known value, and you will instantly see the results in 4 other units.

While this simple tool converts from one unit to another, the speed calculator works out speed based on time and distance. If you are a sports enthusiast, you may find our running pace calculator useful .

What is speed?

The speed of an object is the distance it covers in a certain amount of time, without any regard to the direction of travel. The related term, velocity, uses vectors or positive and negative values to indicate direction.

Two cars traveling in opposite directions, illustrating the difference between speed and velocity.
No matter which direction the car travels, the speed is always 40 mph. The velocity, on the other hand, is either positive or negative, depending on the direction it is traveling.

For example, if in an hour you drive 🚗 40 miles, then your speed (at least your average speed) is 40 miles per hour (mph).

Units of speed

You may not be familiar with all of the units present in this speed conversion calculator. Feet per second and miles per hour are units commonly used in countries that use the imperial system, such as the United States, the United Kingdom, and Australia. On the other hand, meters per second and kilometers per hour are the units of choice for those nations that use the metric system, i.e., the rest of the world.

If you are looking to take to the high seas, then knots are your unit of choice (they are used regardless of your affiliation to the imperial or metric systems). One knot equals one nautical mile per hour (approximately 1.151 mph).

How to convert between units of speed? - speed conversion

To convert from one speed unit to another, it is simply a case of multiplying the speed by the correct conversion factor. In equation form, we can write:

converted speed = original speed * conversion factor

So, for example, to convert from mph to kmh (miles per hour to kilometers per hour), we use a conversion factor of 1.609344. Let's try it out and convert 200 mph to kmh:

speed in kmh = 200 mph * 1.609344 ≈ 322 kmh

Another example is to convert meters per second to miles per hour, which has a conversion factor of 2.23693629. To illustrate this example, let's take Usain Bolt's record 100 meter run of 8.70 seconds. Dividing 100 meters by 8.70 seconds gives a speed of 11.5 m/s. The conversion to mph is then given by:

speed in mph = 11.5 m/s * 2.23693629 ≈ 25.7 mph

Below is a table of the conversion factors for typical speed unit conversions.

Unit conversion Conversion factor
ft/min to m/s 0.00508
ft/s to m/s 0.3048
ft/s to mph 0.681818
km/h to m/s 0.27777778
m/s to km/h 3.6
m/s to mph 2.23693629
mi/hr to m/s 0.44704
mph to ft/s 0.44704
mph to kmh 1.609344

How to use this speed converter?

By default, the speed conversion calculator displays eleven of the most popular units of speed people use in their everyday lives. However, we also have seven other units of speed to explore. Here's how:

  1. Enter your speed into one of the rows showing a commonly used unit, either in the imperial, metric, or other section of the speed converter.
  2. In any one of the other rows, click on the unit and a drop-down menu will appear.
  3. The converter then allows you to choose from the full list of units used in that category of speed units.
  4. The speed converter will then display your speed in the unit you chose.
  5. As a bonus, the speed converter also shows the pace of the speed in various units. Pace flips the speed formula around and states the speed in the amount of time per unit distance. We often use it to measure and compare running speeds in athletics.

ft/s to m/s conversion and m/s to ft/s conversion

To convert ft/s to m/s use the following equation:

speed in m/s = speed in ft/s * 0.3048

For example, a gazelle can reach a top speed of 70 ft/s. What's that in m/s?

speed of gazelle in m/s = 70 * 0.3048 ≈ 21 m/s

To perform the reverse conversion, m/s to ft/s, the equation is:

speed in ft/s = speed in m/s * 3.2808399

For example, a cheetah can reach speeds of 30.690 m/s. What's that in ft/s?

speed of cheetah in ft/s = 30.690 * 3.2808399 ≈ 100.69 ft/s

m/s to mph conversion and mph to m/s conversion

To convert m/s to mph use the equation:

speed in mph = speed in m/s * 2.23693629

For example, a skydiver's belly first terminal speed is 53 m/s. What's that in mph?

speed of skydiver in mph = 53 * 2.23693629 ≈ 120 mph

To perform the reverse conversion, mph to m/s, use the equation:

speed in m/s = speed in mph * 0.44704

For example, a Porsche 911 GT2 has a top speed of 204 mph. What's that in m/s?

top speed of Porsche in m/s = 204 * 0.44704 ≈ 91.2 m/s

km/h to m/s conversion and m/s to km/h conversion

To convert km/h to m/s use the following formula:

speed in m/s = speed in km/h * 0.27778

For example, a high-speed TVG train has a top speed of 320 km/h. What's that in m/s?

speed of TVG train in m/s = 320 * 0.27778 ≈ 88.9 m/s

To perform the reverse conversion, m/s to km/h, the formula to use is:

speed in km/h = speed in m/s * 3.6

For example, the speed of sound is 343 m/s. What's that in km/h?

speed of sound in km/h = 343 * 3.6 = 1,234.8 km/h

mph to ft/s conversion and ft/s to mph conversion

The equation to convert mph to ft/s is:

speed in ft/s = speed in mph * 1.46666667

For example, the maximum speed of an F-16 jet fighter plane is 1,500 mph. What's that in ft/s?

speed of F-16 jet in ft/s = 1500 * 1.46666667 = 2,200 ft/s

To perform the reverse conversion, ft/s to mph, use the equation:

speed in mph = speed in ft/s * 0.68181818

For example, a bolt of lightning can travel up to 320,000 ft/s. What's that in mph?

speed of lightning in mph = 320,000 * 0.68181818 ≈ 220,000 mph

Piotr Małek and Steven Wooding