A
chain (ch) is a
unit of
length. It measures 66
feet, or 22
yards, or 100
links, or 4
rods (20.1168
m). There are 10 chains in a
furlong, and 80 chains in one
statute mile. An
acre is the area of 10 square chains (that is, an area of one chain by one furlong). The chain has been used for several centuries in Britain and in some other countries influenced by British practice.