Bathroom scales measure weight, not mass. Weight is a measurement of the force of gravity on an object, while mass is the amount of matter in an object. A bathroom scale measures your body's weight when you stand on it, which can be used to calculate your body mass index (BMI). The unit for measuring weight is usually kilograms or pounds, depending on where you live. To accurately measure your BMI and other health metrics, it’s important to use a reliable digital scale that provides accurate readings.