Weight (mass) units conversion for metric, US customary and imperial measurement systems including several commonly used historical units.
Mass is defined as the amount of the matter an object has. Weight is the force that mass has because of the gravity.
In metric system (SI), the base unit of mass is kilogram (equals to 2.20462 pounds). Other common metric mass units are gram, milligram and ton. In imperial and US customary system, common mass units are ounce, pound and stone.