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Speed or Velocity Conversion Calculator
What are Speed and Velocity
Speed is the rate of change in position of a moving quanity, without factoring direction into the equation. Walk forwards or backwards 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 backwards again: your velocity would be negative 2 m/s, although your speed would still be positive.
For most science applications, the SI unit for speed and velocity is meters per second (m/s), although kliometers per hour (km/h) are 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 Pascals. 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 inch 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.
| To Convert from Unit |
Unit Symbol |
and Convert to ( m/s ) |
Multiply by ( m/s / Unit ) |
|---|---|---|---|
| centimeter per minute | cm/min | meter per second | 0.0001667 |
| centimeter per second | cm/s | meter per second | 0.01 |
| foot per hour | ft/h | meter per second | 8.46667E-05 |
| foot per minute | ft/min | meter per second | 0.00508 |
| foot per second | ft/s | meter per second | 0.3048 |
| inch per minute | in/min | meter per second | 0.000423333 |
| inch per second | in/s | meter per second | 0.0254 |
| kilometer per hour | km/h (kph) | meter per second | 0.2777778 |
| kilometer per second | km/s | meter per second | 1000 |
| knot (nautical mi/h) | kn | meter per second | 0.5144444 |
| knot (UK) | kn | meter per second | 0.5148 |
| meter per hour | m/h | meter per second | 0.0002777778 |
| meter per minute | m/min | meter per second | 0.01667 |
| meter per second | m/s | meter per second | 1 |
| mile per hour | mi/h (mph) | meter per second | 0.44704 |
| mile per minute | mi/min | meter per second | 26.8224 |
| mile per second | mi/s | meter per second | 1609.344 |
| speed-of-light (vacuum) | c | meter per second | 299792458 |
| yard per hour | yd/h | meter per second | 0.000254 |
| yard per minute | yd/min | meter per second | 0.01524 |
| yard per second | yd/s | meter per second | 0.9144 |
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/