As shown in the figure, the Vernier caliper consists of an inside jaw, an outside jaw, a main scale, a sliding Vernier and a tail. This instrument comes in handy to measure the internal diameter or the external diameter of objects. It is a good practice to consult the procedure of using the Vernier caliper and get a first hands experience on how to use this instrument as a pro on your first attempt.

**Steps in using a Vernier caliper:**

- Check the zero error. The Vernier caliper needs to be checked for a zero error. As the reading taken will need to be adjusted through calculations and considerations of the zero error will have to be adjusted in the final reading.
- Position the object correctly within the Vernier caliper jaws by using the inside jaws and the outside jaws or the tail to take the measurements.
- Read the main scale. The main scale on the Vernier caliper will give you a reading in a whole number plus the first decimal. The reading is taken similar to a normal ruler. If the result is coming between two lines, just use a smaller value. Don’t try to estimate the value.
- Read the Vernier scale reading which is coinciding with the markings on the main scale. Find the first mark that is lining up with the main scale. If the scale represents 0.01 inch increments then the result is 0.014”. the line aligning on the main scale makes no difference.
- Now take the sum of the main scale reading and the Vernier scale reading. Make sure that you have considered the units on the scale. For instance, the reading on the main scale is coming up to 2.6 inches and the Vernier scale is reading 0.014 inches. When we add both the readings, we will get 2.614 inches. Its is not necessary that the digits will be lining up neatly for the reader to take readings. For instance, the main scale reading would be coming up to 0.85 cm, while the Vernier scale reading would be coming up to 12 on a 0.01 cm scale. When the readings are added up, the final reading would come to 0.85 + 0.012. which will be 0.862 cm.

To Help you better understand the parts of the vernier caliper and how they fit together the following image may prove useful:

**Zero error:**

The instrument must be checked for zero errors if any. This is to make sure that the two zero marks are coinciding with each other when the instrument is not under use. The zero error is indicated by the reading on the Vernier scale.

There will be three situations in case of a zero error. Either there will be no zero error, or there will be a negative zero error or a positive zero error. In case of no zero errors there will be no change in the standard calculations. but in case of a positive or a negative zero error, the zero error value will either be added or subtracted from the final reading.

In case of a negative zero error, the value difference will be added in the value recorded from the Vernier caliper, while in case of a positive zero error, the value difference will be added in the recorded value to get the actual value, which is void of a zero error.

**In case of no zero error:**

In this case both the zero marks will be coinciding with each other. Now move the bottom slider to a certain position and take the reading. Check your reading by selecting show reading at the bottom left.

**In case of a positive zero error:**

Clicks reset and then move the slider up to any position and then take the zero error reading. Move the bottom slider to a certain position and take the reading and then calculate the actual reading. Select the show reading button.

**In case of a negative zero error:**

Clicks reset and then move the right slider to any position and then take the zero error reading. Now move the bottom slider to a certain position and then take the reading and then calculate the actual reading. Select the show reading button.