A Vernier caliper is read by looking at aligned tick marks that read centimeters, millimeters and tenths of a millimeter on a sliding scale, according to the Southern Methodist University Department of Physics. The error of a Vernier caliper is 0.05 millimeters.
The main scale of a Vernier caliper is the reading that is to the left of zero on the tenth of a millimeter sliding scale. Then, the next reading is taken by the closest congruent line. If the 0.08 centimeter line is most closely aligned to another line on the scale below it, the final reading includes 0.08 centimeter. The tenth of a millimeter line is read by alignment only, no matter what the millimeter reading is below it. If no line exactly matches up, the closest one is taken, and the reading is then approximated.
One common mistake occurs when someone tries to read the closest line to zero, rather than the one to the left of the zero line. Another possible mistake happens when someone finalizes the tenths of a millimeter mark on a Vernier caliper. These readings are made by rounding to the nearest mark as if there was no such precision with the instrument.
A Vernier caliper measures diameters and widths of objects between two jaws that close tightly on objects. The tighter the calipers, the more precise the measurements.