Kilogram

Definition: The kilogram (symbol: kg) is the base unit of mass in the International System of Units (SI). One kilogram is equal to 1,000 grams or approximately 0.157473 stone. It is defined using Planck's constant, making it based on a fundamental constant of nature rather than a physical object.

History/origin: The kilogram was first defined in 1795 as the mass of one liter of water at its freezing point. In 1889, the International Prototype of the Kilogram (IPK), a cylinder made of platinum-iridium alloy, was introduced as the standard and kept in Sèvres, France. On May 20, 2019, the kilogram was redefined based on Planck's constant, eliminating the need for a physical prototype and ensuring greater precision and stability. This redefinition marked a significant milestone in metrology.

Current use: The kilogram is the standard unit of mass used worldwide in science, engineering, and everyday life. It is used to measure body weight, food quantities, luggage weight, industrial materials, and vehicle weight. In countries that have adopted the metric system, the kilogram has replaced the pound as the primary unit of mass. The kilogram is essential in international trade, manufacturing, healthcare, sports, and scientific research across all disciplines.

Stone

Definition: The stone (symbol: st) is a unit of mass in the imperial system, primarily used in the United Kingdom and Ireland. One stone is equal to 14 pounds or approximately 6.35029 kilograms. It is commonly used for measuring human body weight in these regions.

History/origin: The stone has been used as a unit of measurement in England since at least the 14th century. Its exact weight varied depending on the commodity being measured, with different stones used for wool, cheese, meat, and other goods. The stone was standardized at 14 pounds in 1835 as part of the British Weights and Measures Act. The term "stone" comes from the historical practice of using stones as standard weights for trade and commerce.

Current use: The stone is primarily used in the United Kingdom and Ireland for measuring human body weight. In these countries, people commonly express their weight in stones and pounds (e.g., "10 stone 5 pounds" or "10st 5lb"). While most other countries use kilograms for body weight, the stone remains deeply ingrained in British and Irish culture. It is rarely used for other purposes and has been largely replaced by kilograms in official contexts, though it persists in everyday conversation about personal weight.

Kilogram to Stone Conversion Table

How to Convert Kilogram to Stone