<P> Although customary units are used more often than metric units in the U.S. , the SI system is used extensively in some fields such as science , medicine , the military , automobile production and repair , and international affairs . Post 1994 federal law also mandates most packaged consumer goods be labeled in both customary and metric units . Still , most Americans are unable to make metric conversions , but smartphone apps can help ( e.g. on iOS and Android ) . </P>
who uses the metric system in the us
science medicine the military automobile production and repair international affairs