The British distance measure is a system of units used to measure length. The three most commonly used units are the METRE (5 letters), the parsec (6 letters) and the mile (4 letters). The METRE is the base unit of length in the International System of Units (SI) and is equal to approximately 3.28 feet. The parsec is a unit of length used in astronomy and is equal to about 3.26 light-years. The mile is an imperial unit of length equal to 1, 760 yards or approximately 1.61 kilometres.