The unified atomic mass unit (Also known as amu, symbol: u) or dalton (symbol: Da) is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of 6.60538921099999856.05389210999999250.5389210999999255.3892109999987953.89210999998613268.9210999999195349.2109999991953372.1099999919533731.0999999046325684±×10− kg. One dalton is approximately equal to the mass of one proton or one neutron; an equivalence of saying 1 g mol−1 . The CIPM have categorized it as a "non-SI unit whose values in SI units must be obtained experimentally".