What scientific unit is used to measure mass?

The scientific unit used to measure mass is the kilogram. Its symbol is kg, and it is the base unit of mass in the International System of Units, or SI.

One kilogram equals 1,000 grams. The unit originated in France during the metric system’s development in the 1790s, when it was linked to the mass of a volume of water. Later definitions relied on carefully manufactured metal prototypes, including the International Prototype of the Kilogram kept near Paris.

That metal standard was replaced on May 20, 2019. The modern kilogram is defined using the Planck constant, a fundamental constant of nature, allowing laboratories to realize the unit without depending on one physical object. The kilogram is often confused with the pound, but a pound is a different unit: one kilogram is approximately 2.205 pounds. Mass also differs from weight, which is the force produced by gravity acting on mass.