A balance scale is a device used to measure weight or mass. It is commonly used to compare the weights of objects or to weigh objects by balancing them with standard weights. The balance scale is based on the principle of balance, which states that two objects of equal weight will balance each other out when placed on opposite sides of a fulcrum. There are several types of balance scales, including beam scales, spring scales, and digital scales.

Balance scales are used in a variety of settings, including laboratories, pharmacies, and classrooms. They are used to measure the weight or mass of an object, and with proper calibration, precision balance scales can deliver consistently accurate, precise measurements from 0.0001g (0.1mg) to 0.1g. Balance scales can also measure the densities of various liquids, have built-in interference reduction to minimize fluctuations, and can calculate percentage weight in real-time.

To use a balance scale, the object to be weighed is placed on one side of the scale, and objects with known weights are added to the other side until the beam connecting the pans is level. The weight of all the objects that were added to the second pan is calculated, and that value is the weight of the object in the first pan. Some balance scales are designed for laboratory use and are small enough to sit on a table, while others are designed for personal use and are large enough for a person to stand on.