The standard unit of mass in the International System of Units (SI) is the kilogram, which is denoted by the symbol kg.

Other units of mass include the gram (g), which is 1/1000 of a kilogram, and the metric ton (t), which is 1000 kilograms. In the imperial and U.S. customary systems, units of mass include the ounce (oz), pound (lb), and ton.