The charge of a strange quark, as well as any other quark, is measured in units of elementary charge (e). The elementary charge, denoted as e, is approximately equal to 1.602 x 10^-19 coulombs (C).
The strange quark has an electric charge of -1/3e, which means it carries one-third of the negative elementary charge. This charge is in contrast to the up quark and down quark, which have electric charges of +2/3e and -1/3e, respectively. These three quarks form the building blocks of protons and neutrons, which are composite particles found in the nucleus of atoms.