The main basic errors in the case of an electromechanical instrument are due to friction between moving components and fixed elements, mechanical inertia, thermal inertia, reading errors, in particular a parallax error (if the pointer is some distance from the surface of the scale and the reader cannot position himself face-on to the surface).

In the case of high-quality instruments, the manufacturer supplies a calibration curve: this shows the relationship between the values of the quantity measured and the values shown by the instrument. If necessary, correction curves may be applied to correct the results if one or more material quantities are outside the reference conditions.