Distance, like every other quantity, has many units. It can be measured in meters, in kilometers and so on. However, the international system of units gave each quantity a specific unit. The other units are all modifications of the first one. Therefore the standard unit for the distance is meters. It can then be changed it many other units such as cm, Km, mm and so on.

Depending on the multiple, the distance is converted into bigger numbers. Likewise, other quantities such as weight also have specific units such as grams which can then be interconverted into smaller or larger units according to preference.