How to Read a Vernier Caliper

A Vernier caliper is a small mechanical device used to take precise measurements. It has upper jaws that measures internal dimensions, and lower jaws that measures external dimensions. There are many different types of calipers, and the Vernier caliper makes use of a Vernier scale for measuring precise dimensions. It can measure accurately at a hundredth of a millimeter and a thousandth of an inch.

The Vernier caliper has 2 scales: the main scale, which shows a reading in millimeters or inches, and the Vernier scale that has 10 equal divisions. The final reading is based on the readings on the 2 scales.

Step 1. Familiarize with the Vernier Caliper’s Parts

Study the parts of the Vernier Caliper. Take note that there are 2 scales on the device: one on the upper part and one on the lower part. There are also 2 movable jaws. As the jaws move, so does one of the measuring scales. The larger jaws can be used to measure external dimensions. For internal dimensions, such as internal spaces or holes, make use of the smaller jaws. The tick marks on the main scale refer to one unit of measurement; 2 ticks after zero on the main scale reads as 2.0 (inches, millimeters, centimeters depending on the unit of measurement being used).

Step 2. Calibrate

Calibrate a Vernier caliper to get a precise reading. Never forget this part. The main scale and the Vernier scale should match at the zero marks. Completely close the jaws of the caliper to check if the zero marks are aligned with each other. Make adjustments to the Vernier if the zeros do not match.  Close the bolts of the caliper tightly after the zeros are aligned. If it is not possible to correct the misalignment, take note of the error. If the error is a positive (+) value (Vernier zero is to the right of the main zero), subtract it to the final measurement to get the precise measurement. If the error is a negative (-) value (Vernier zero is to the left of the main zero), add it to the final measurement.

Step 3. Measure an Object

Take an object and place the caliper’s jaws around it. Take a good look at where the Vernier scale rests. Check for the tick on the Vernier scale that is lined up perfectly with the main scale. Use the Vernier scale’s zero mark as reference to determine the number of ticks on the main scale.

Step 4. Read the Measurement

Read the whole number on the main scale nearest to the Vernier caliper’s zero mark. This number should be read on the left of the Vernier scale’s zero mark. Now you have an approximate reading. To get a precise reading, get the number of the tick on the Vernier scale that perfectly aligns with a tick on the main scale. In the reading, place a decimal point after the whole number and add the tick number taken from the Vernier scale to the right of the decimal point and you get a precise reading.