A unit of length is a way of measuring length or distance.
Common units of length in the International System of Units (SI) are:
But there are a lot of units that do not fit in the SI-System:
Common Imperial units and U.S. customary units of length include:
In addition, the following are used by mariners:
Surveyors in the United States continue to use:
Horse racing keeps alive:
Astronomical measure uses:
Physics also uses:
Old units of distance are: