No, the atomic mass unit (amu) is not considered an SI (International System of Units) unit for atomic mass. The SI unit for atomic mass is the kilogram (kg). However, the atomic mass unit is a commonly used unit in the field of atomic and molecular physics to express the relative masses of atoms and molecules. One atomic mass unit is defined as 1/12th the mass of a carbon-12 atom. The atomic masses of elements and isotopes are often expressed in atomic mass units for convenience.