# Speed Conversion Calculator

## Calculator Use

Speed is the rate of change in position of an object, regardless of direction of travel. Walk forward or backward at 2 meters per second, and your speed is just that: 2 m/s. Velocity is speed in the context of direction. Say you were walking backward again; your velocity is **negative** 2 m/s, although your speed is still positive.

For most science applications, the SI unit for speed and velocity is meters per second (m/s), although kliometers per hour (km/h) is sometimes used when measuring the speed of vehicles. The English system usually expresses speed as miles per hour (mph) or sometimes feet per second (ft/s), while marine vessels typically use knots, or nautical miles per hour.

## How to Convert Units of Speed

Conversions are performed by using a conversion factor. By knowing the conversion factor, converting between units can become a simple multiplication problem:

**S * C = E**

Where **S** is our starting value, **C** is our conversion factor, and **E** is our end converted result.

To simply convert from any unit into meters per second^{}, for example, from 5 mph, just * multiply by* the conversion value in the right column in the table below.

5 mph * 0.44704 [ (m/s

^{}) / (mph) ] = 2.2352 m/s^{}

To convert from m/s ^{} into units in the left column * divide by* the value in the right column or, multiply by the reciprocal, 1/x.

2.2352 (m/s) / 0.44704 [ (m/s

^{}) / (mph) ] = 5 mph

To convert among any units in the left column, say from A to B, you can multiply by the factor for A to convert A into meters per second ^{} then divide by the factor for B to convert out of meters per second. Or, you can find the single factor you need by dividing the A factor by the B factor.

For example, to convert from miles per hour to kilometers per hour you would multiply by 0.44704 then divide by 0.2777778. Or, multiply by 0.44704/0.27777778 = 1.6093439. So, to convert directly from mph to km/h (kph), you multiply by 1.6093439.

Unit

Symbol

( m/s

^{2}or m/(s·s) )

( m/s

^{2}/ Unit )

## References/ Further Reading

The National Institute of Standards and Technology (NIST) - *The NIST Guide for the use of the International System of Units* - Appendix B, subsections B.8 Factors for Units Listed Alphabetically and B.9 Factors for units listed by kind of quantity or field of science.

Lide, David R., Daniel (Editor-in-Chief). *CRC Handbook of Chemistry and Physics, 89th Edition* New York, NY: CRC Press, p. 1-28, 2008.

Wikipedia contributors. "Conversion of units" Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, last visited 26 Jun. 2011.

*How Many? A dictionary of units of measurement* at http://www.unc.edu/~rowlett/units/

**Cite this content, page or calculator as:**

Furey, Edward "Speed Conversion Calculator"; from *http://www.calculatorsoup.com* - Online Calculator Resource.