WEBThe micrometre ( Commonwealth English) as used by the International Bureau of Weights and Measures; [1] SI symbol: μm) or micrometer ( American English ), also commonly known by the non-SI term micron, [2] is a unit of length in the International System of Units (SI) equalling 1 × 10−6 metre (SI standard prefix "micro-" = 10−6 ); that is ...