This chapter states the requirements for balances used for materials that must be accurately weighed (see General Notices, 8.20 About). Unless otherwise specified, materials must be “accurately weighed” using a balance that is calibrated over the operating range and meets the requirements for Repeatability and Accuracy. For a balance used for other applications described in a monograph, repeatability and accuracy should be commensurate with the requirements for the balance's use. The scope of this chapter does not cover balances used for manufacturing. To ensure the balance remains fit for its intended use throughout its life cycle, calibration and performance checks should be carried out periodically, with performance checks performed between calibrations. The frequencies of calibration and performance checks are risk-based and defined in the user's quality management system.