The instruments used to measure the mass of an object are scales and balances. Several different types of scales and balances exist and are used based on the type of measurement needed.
The two main methods of massing a sample are taring and subtraction. Taring is performed by zeroing out a balance with a container inside or atop the balance, as appropriate, then adding the sample. The mass measurement on the display is the mass of the sample only. The subtraction method involves measuring the mass of a sample by calculating the difference in the mass of a container with and without the added sample. The balance should be set to zero before the empty container is added to get accurate results with the subtraction method.