How to read a vernier caliper

If you are wondering how to read a vernier caliper, this section of Science Experiments website is for you. Learn how to read a vernier caliper here. A vernier caliper is used to measure very accurate linear measurements. Vernier calipers are widely used in science experiments and in manufacturing for quality control measurements.

Two scales on Vernier calipers: Main Scale and Vernier Scale

Vernier calipers have two graduated scales. The main scale is like a ruler. The second scale, called the vernier scale, slides parallel to the main scale and enables readings to be made to a fraction of a division on the main scale.

Two types of Vernier scale

Some vernier calipers are made with 10 divisions on vernier scale. Some vernier calipers are made with 25 divisions on vernier scale. But both types of vernier scale are used the same way.

The main scale of a vernier caliper, where the vernier scale has 25 divisions, has 24 divisions in the same length. This means that the divisions on the vernier scale are shorter than those on the main scale by 1/25 of a division on the main scale.

Some Vernier scales are made with 10 divisions in the same length as 9 divisions on the main scale; the technique of reading such a scale is similar to that described above. A vernier scale can be used to increase the accuracy of angular as well as linear measurements.

Figure 2: Reading a Vernier Caliper and Vernier Scale

How to read a Vernier Caliper

First look at the main scale (the top scale) and see where 0 of the Vernier scale lies. In this example, 0 of the bottom vernier scale is between 20 and 21. So, the reading is between 20 and 21. Then for more accuracy look at the main scale and the vernier scale and see where the two scales line up. In this case, they seem to line up at the third line (3 on vernier scale). So, the reading is 20.3mm.