Metric Units
### Table of Metric Speed 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.

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
### Table of Imperial Speed 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.

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 |