Convert stone to kilograms with our free online converter. One stone equals 6.35029 kilograms, and one stone equals 14 pounds. The stone is a unit of weight still commonly used in the UK for measuring body weight, even though the metric system (kilograms) is the official standard. This conversion is frequently needed when reading medical records (which often use kg), comparing weights with people from other countries, or understanding gym and fitness equipment that uses kg. Our converter supports stones and pounds to kilograms, and the reverse.