Mass spectrometry is considered to be highly accurate. Modern mass spectrometers report measurements to four decimal places and sometimes more. The accuracy of these spectrometers depends on several factors such as resolution, calibration, data analysis methods, and sample preparation. Accurate calibration is important for achieving the highest quality results. Calibration is usually done using reference compounds with accurately determined masses. Proper sample preparation and storage is also important, in order to minimize interference from contaminants. The resolution of a mass spectrometer is also crucial, as higher resolution enables more accurate peak identification and better differentiation of closely spaced peaks.