The table above is based on the
kilogram, the base unit of mass in the
International System of Units (
SI). The kilogram is the only standard unit to include an
SI prefix (
kilo-) as part of its name. The
gram (10−3 kg) is an SI derived unit of mass. However, the
names of all SI mass units are based on
gram, rather than on
kilogram; thus 103 kg is a
megagram (106 g), not a *
kilokilogram. The
tonne (t) is an SI-compatible unit of mass equal to a megagram (
Mg), or 103 kg. The unit is in common use for masses above about 103 kg and is often used with SI prefixes. For example, a gigagram (
Gg) or 109 g is 103 tonnes, commonly called a
kilotonne.
Other units Other units of mass are also in use. Historical units include the
stone, the
pound, the
carat, and the
grain. For subatomic particles, physicists use the mass-equivalent of an
electronvolt (eV). At the atomic level, chemists use the mass of one-twelfth of a carbon-12 atom (the
dalton). Astronomers use the
mass of the sun ().
The least massive things: below 10−24 kg Unlike other physical quantities, mass–energy does not have an
a priori expected minimal quantity, or an observed basic quantum as in the case of
electric charge.
Planck's law allows for the existence of
photons with arbitrarily low energies. Consequently, there can only ever be an experimental upper bound on the mass of a supposedly massless particle; in the case of the photon, this confirmed upper bound is of the order of = .
10−24 to 10−18 kg 10−18 to 10−12 kg 10−12 to 10−6 kg showing grains of sand
10−6 to 1 kg 1 kg to 105 kg s depicted in ''''.
106 to 1011 kg 1012 to 1017 kg 1018 to 1023 kg 1024 to 1029 kg is the most massive planet in the
Solar System.
1030 to 1035 kg 1036 to 1041 kg The most massive things: 1042 kg and greater ==See also==