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The basic unit of mass in the metric system is the kilogram. All the others are multiples or fractions of a kilogram.
In physics, mass is usually measured in kilograms. Metric weighing-scales will usually display mass in kilograms, so this is a likely choice for the measurement of a person's mass.
gram
Mass is measured in kilograms.
How to Convert Metric Units of Mass
How to Estimate and Measure Mass in Metric Units
How to Compare Mass in Different Metric Units
How to Compare Metric Units of Mass