Among the most common measurement instruments include calipers, Gauges, Micrometer and nutrometr. All of them can get fairly accurate results, but even with good instruments there is some measurement error. As a rule, its value is indicated in the data sheet, and that it directly affects the value of the instrument. The lower the error, so, consequently, higher accuracy, It means that the price may differ significantly from the price of a simple model of the same caliper or micrometer. Errors in measurement, but even if you bought the most expensive tool when working with it is not excluded possibility of error. The main causes that lead to inaccurate data in the measurement, is the inability to use the tool, use a damaged instrument (including a zero mark with a whipped egg on the scale) contamination of working surfaces of the instrument and measured object, the measurement of hot or cold items. It is therefore very important to keep measuring instruments for a protective cartridge, remove promptly from their pollution, to verify that the original mark on the scale of zero. A standard temperature at which the measurements are carried out parts (especially metal), is considered to be +20 C.

Another way to reduce error is a series of measurements of one parameter and calculating the arithmetic mean value. This practice is widely applied in the use of inexpensive instruments, it did not interfere in the measurement professional models whose error is extremely small. Vernier scale, to enhance the accuracy of some instruments are equipped with auxiliary scale.