In the metric system, the unit used to measure mass is the kilogram (kg).
The kilogram is defined as the mass of a specific platinum-iridium cylinder known as the International Prototype of the Kilogram. It serves as the base unit of mass in the International System of Units (SI). Other units for measuring mass in the metric system include grams (g), where 1 kilogram equals 1,000 grams. The metric system is widely used around the world, especially in scientific contexts, because of its simplicity and ease of conversion between units.