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How do you read a metric vernier caliper?

How to read a metric vernier caliper?

Main scale and vernier scale on a vernier caliper

If you are used to using a dial caliper, it can be a little tricky to get used to reading a vernier caliper. However, once you get the hang of it, it is a straightforward way of taking measurements quickly and accurately!


Although the vernier caliper can be used to measure a variety of different dimensions, the way in which it is read is always the same.


The reading on a vernier caliper is a combination of the value shown on the main scale and the value indicated on the sliding vernier scale.

Guide to Reading a Metric Vernier Caliper

Step 1 – Look at the main scale

When taking a measurement, you should first read the value on the main scale. On a metric vernier caliper, this will be given in millimetres (mm).


The smallest value that can read from the main scale is 1mm (indicated by a single increment).

1 increment on a vernier scale is 1mm.

The value on the main scale is the number immediately to the left of the 0 marker of the vernier scale.


In this instance, this value is 27mm.


As the zero is almost touching the 28mm mark, we can estimate that the distance between the jaws is closer to 28mm than 27mm.

Measurement of 27mm on a vernier scale.

Step 2 – Look at the vernier scale

Next, look at the vernier scale. The vernier scale of a metric vernier caliper has a measuring range of 1 mm. In the example we will be looking at, the vernier scale is graduated in 50 increments.


Each increment represents 0.02mm. However, some vernier scales are graduated in 20 increments, with each one representing 0.05mm.

The ruler side of a vernier caliper.

When reading the vernier scale, identify the increment that lines up most accurately with an increment on the main scale. This value will make up the second part of your measurement.


In the example, the increments of both scales coincide at the 0.8mm on the vernier scale.

Both scales coincide at 0.8mm on a vernier caliper.

Step 3 – Add both values together

To get your total reading, add both the value from the main scale and the value from the vernier scale together.


e.g. 27 + 0.8 = 27.8


So, the distance between the jaws of the vernier caliper is 27.8mm.

Example of how to measure using a vernier caliper with a reading of 27.8mm.

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