The accuracy of precision balances is given by the combination of their trueness and precision. The trueness of values measured on precision balances describes how close they are to the well-defined mass of a calibrated test weight. Precision refers to the range of variation of repeated measurements made under the same conditions on the same precision balance. Repeatability is the measure of precision typically reported on datasheets and should not be confused with the term readability. Readability, down to 0.1 mg for precision balances, is only a first indication of performance.