The stone (abbreviation st[1]) is a unit of measure equal to 14 pounds avoirdupois (about 6.35 kg[nb 1]) used in Great Britain and Ireland for measuring human body weight. In many Northwestern European countries the stone was formerly used for trade, though its value ranged from about 5 to 40 local pounds (3 to 15 kg). With the advent of metrication from the mid-19th century on, it was superseded by the kilogram. It remained in limited use for trade in the United Kingdom and in Ireland until prohibited by the Weights and Measures Act of 1985