 One primary advantage of the International System of Units is simply that it is international, and the pressure on countries to conform to it grew as it became increasingly the international standard.It also simplifies the teaching and learning of measurement as all SI units are based on a handful of base units (in particular, the metre, kilogram and second cover the majority of everyday measurements), using decimal prefixes to cover all magnitudes.This contrasts with pre-metric units, which largely have names that do not relate directly to one another (e.g.