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Metric Units

The main metric unit of speed is metres per second (m s-1, m·s-1, m/s, mps) however few people will actually use this on a day to day basis, instead they will use kilometres per hour (kph, kmph, km/h, km h-1, km·h-1). One metre per second is 3.6 kilometres per hour.

For some uses in astronomy kilometres per second (kps, kmps, km/s, km s-1, km·s-1) are used, with the speed of light being 299,792.458 km/s or 299,792,458 m/s.

Table of Metric Speed Units

Unit Abbreviation As m/s Useful Information
millimetres per second mm s-1 0.001 Rarely used
centimetres per second cm s-1 0.01 Rarely used
decimetres per second dm s-1 0.1 Rarely used
metres per second m s-1 1 Used for many scientific velocity calculations
decametres per second dam s-1 10 Rarely used
hectometres per second hm s-1 100 Rarely used
kilometres per second km s-1 1000 Used in astronomical measurements and calculations
kilometres per hour km h-1 0.27778 Commonly used for road speed limits, alternate abbreviations include kmph and kph
Imperial Units

For those countries that use imperial distances the most common unit of speed is miles per hour (mph, miph, m/h, mi/h). Occasionally inches per second (in/s, ips), feet per second (ft/s, fps), yards per second (yd/s, yps) and miles per second (mi/s, m/s, mps) are also seen. It is extremely rare to see the -1 superscript notation used for imperial speed unit abbreviations.

Table of Imperial Speed Units

Unit Abbreviation As m s-1 Useful Information
inches per second in/s 0.0254 Rarely used
feet per second ft/s 0.3048 Rarely used
yards per second yd/s 0.9144 Rarely used
miles per second mi/s 1609.344 Rarely used
miles per hour mph 0.44704 Commonly used for road speed limits. Other abbreviations include mi/h, miph, m/h
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