What unit measures mass according to the International System of Units (SI)?

The International System of Units (SI) defines the base unit for mass as the kilogram (kg). This unit is fundamental in scientific and technical contexts and serves as the standard reference for mass measurements across various disciplines.

Although grams (g) are also an SI unit for mass, they are considered a derived unit, where one kilogram is equal to 1000 grams. Therefore, while grams are used extensively, the kilogram is the primary unit established by SI for mass.

On the other hand, the pound (lb) and ounce (oz) are units of mass used primarily in the Imperial system, which is not part of the SI. Hence, while they are commonly recognized, they do not conform to the SI standards for mass measurement.