What is the SI unit of mass?

The SI unit of mass is the kilogram (kg). The kilogram is defined as the base unit of mass in the International System of Units (SI), and it is widely used in scientific and engineering applications. In the metric system, the kilogram is fundamental because it serves as the standard measure for mass from which other units are derived. For instance, 1 kilogram is equivalent to 1,000 grams, which allows for scalability within the metric system. The definition of the kilogram has been established based on the physical constant related to the Planck constant, further emphasizing its importance in precise measurements. Other units like grams, tons, and ounces are derived from or used in different contexts but do not serve as the base unit in the SI framework.