The femtogram is an SI unit of mass (symbol fg) defined as:

1 fg = 1 × 10^-18 kilogram ( = 1 × 10^-15 gram)

A femtogram is one quadrillionth (1/1000000000000000) of a gram. It is derived from the Danish or Norwegian word femten, or fifteenth, referring to 10^-15 gram

attogram << femtogram << picogram