Worldwide, there has been a long process of independent conversions of countries from various local and traditional systems, beginning in France during the 1790s and spreading widely over the following two centuries, but the metric system has not been fully adopted in all countries and sectors.
在全世界范围内，各国由各种地方和传统计量制度各自独立地向公制转变已有很长的历程；1790年代发端于法国，并在随后的两个世纪中广泛传播，但公制并未在所有国家和领域得到完全采用。