The base SI unit of mass, abbreviated kg, equal to 1,000 grams. It is the standard unit for weighing ingredients in commercial food production, nutrition labelling of bulk products, and body weight in clinical settings. The kilogram was historically defined by a physical platinum-iridium cylinder kept in France, but since 2019 it has been defined by the fixed numerical value of the Planck constant, linking it to fundamental physics. In kitchens and factories, scales calibrated in kilograms ensure accurate formulation, portion control, and regulatory compliance. Nutritional recommendations, such as protein needs per kilogram of body weight, rely on this unit.