Length

Length
The metric length of one kilometre is equivalent to the imperial measurement of 0.62137 miles.
Common symbols	l
SI unit	metre (m)
Other units	see unit of length
Extensive?	yes
Dimension	${\displaystyle {\mathsf {L}}}$

Length is a measure of distance. In the International System of Quantities, length is a quantity with dimension distance. In most systems of measurement a base unit for length is chosen, from which all other units are derived. In the International System of Units (SI) system the base unit for length is the metre.^[1]

Length is commonly understood to mean the most extended dimension of a fixed object.^[1] However, this is not always the case and may depend on the position the object is in.

Various terms for the length of a fixed object are used, and these include height, which is vertical length or vertical extent, width, breadth, and depth. Height is used when there is a base from which vertical measurements can be taken. Width and breadth usually refer to a shorter dimension than length. Depth is used for the measure of a third dimension.^[2]

Length is the measure of one spatial dimension, whereas area is a measure of two dimensions (length squared) and volume is a measure of three dimensions (length cubed).