Accuracy refers to the freedom from error or mistake of a measuring device. How accurate is a volumetric flask as a measuring instrument?
The accuracy of a volumetric flask depends on its capacity.
Volumetric flasks come in two classes, and in sizes ranging from 1 mL to 6 L.
Class A flasks are used in analytical labs. They are more accurate and must be marked with the letter "A".
Class B flasks are used for educational work or whenever extreme accuracy is not required. Their volumetric tolerances must be within twice the specified Class A tolerances.
They must all be used at their calibration temperatures.
The specifications for some common capacities of Class A flasks are:
Note that the absolute tolerance increases, but the relative tolerance decreases, as the capacity increases.