Convert Ounce to Kilogram

The ounce traces its origins to ancient Roman times, where it was based on the uncia, which was 1/12 of a Roman pound (libra). The term "ounce" comes from the Latin "uncia", meaning one-twelfth. In medieval Europe, the ounce evolved as a standardized unit of weight, especially in trade. By the 14th century, the Avoirdupois ounce became the standard for most goods in England, which is equivalent to about 28.35 grams. This measurement was later adopted in the United States and other countries using the imperial system.

The kilogram originated during the French Revolution in the late 18th century as part of the metric system's development. Initially, it was defined as the mass of one cubic decimeter of pure water at 4°C, chosen for its universal availability and consistency. In 1799, a physical standard called the Kilogram of the Archives, a platinum cylinder, was created to represent the unit. Later, in 1889, the International Prototype of the Kilogram (IPK), a more precise platinum-iridium cylinder, was adopted as the global standard, stored in France with copies distributed worldwide.

Over time, physical changes in the IPK led to inconsistencies, prompting scientists to redefine the kilogram. In 2019, it was redefined based on the Planck constant (h), a fundamental constant of nature, linking the kilogram to unchanging physical properties rather than a physical object. This modern definition ensures long-term precision and stability for the unit of mass.