Measurements of length and distance are done in many ways. Did you know that you can use the average human body as means to measure? For example, the foot (which is literally the length measurement of an average human foot) is around 25 – 30 cm. This unit of measurement is still in use nowadays. We also use units like **inches** and **yards** which are still in use but they are not the standard units of length measurements.

Distance is defined as the product of speed and time and it can be represented as follows:

d=s×t |

Where,

- d is the distance travelled in m
- t is the time taken to cover the distance in s
- s is the speed in m.s
^{-1}

Most commonly used units of measurement of length are:

- Millimetre
- Centimetre
- Metre
- Kilometre

Following is the table explaining the relationship between all these units:

Abbreviation |
Fullform |
Equivalent |

mm | millimetre | 10mm = 1cm 1000mm = 1m |

cm | centimetre | 100cm = 1m |

m | metre | 1000m = 1km |

km | kilometre | 1000m = 1km |