Tsarin SI (wanda aka fi sani da International System of Units) tsari ne na zamani na tsarin awo, kuma shi ne tsarin ma'aunin da aka fi amfani da shi a duniya. Ya dogara ne akan raka'a guda bakwai: mita (tsawon), kilogram (mass), na biyu (lokaci), ampere (lantarki na yanzu), kelvin (zazzabi mai zafi), tawadar (yawan abu), da candela (ƙarfin haske). Ana amfani da waɗannan raka'o'in tushe don samo duk sauran raka'o'in ma'auni, kamar Newton (ƙarfi) ko Joule (makamashi). Ana amfani da tsarin SI a cikin mahallin kimiyya da fasaha, kuma kusan kowace ƙasa a duniya ta karɓe shi a matsayin tsarin ma'auni.