The number of stone equivalent to 20 kilograms is 3.1495, typically rounded to 3.15 stone. This is based on the fact that 1 kilogram in the metric system of measurement equals 0.16 stone. Stone are a unit of weight previously used in Great Britain and Ireland.
Many people in the United Kingdom and Ireland still refer to weight in stone, even though it was discontinued as an official unit of weight measurement by the Weights and Measures Act of 1985. The system was originally used in commerce and trade and dated back to ancient civilizations that used a literal stone for measuring weight. In the U.S. standard or imperial system, 1 stone equals 14 pounds.