B. Vernier Scales

A vernier scale is included on some measuring instruments, such as callipers, to increase the precision of the tool. The calliper shown below has a vernier scale for both inches and millimetres and is capable of measuring to the nearest of an inch or the nearest 0.1 mm. The focus of this section will be on metric measurement, but you can try to use the imperial side of the calliper as a challenge.

Vernier Scale

A sliding scale that is used to indicate fractional divisions of a larger scale.

Calliper

A device for measuring external or internal dimensions, as well as depth.

 

To see a larger image of the following measuring tools, place your mouse arrow in front of the images, or on a tablet, tap the image.

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    Vernier Scale

 

To measure with a calliper, adjust it so the ends of the calliper touch the ends of the object. The inside distance, outside distance, and the depth are all read from the same scale.

To read the scale, first determine the value on the fixed scale that is immediately to the left of the 0 on the vernier scale. In the diagram below, this is 2.2 cm.

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    Vernier Scale


Next, you will read the vernier scale to determine a more precise value. This vernier scale shows 10 increments, so the finer measurement is the size of the increments on the fixed scale. This is what the "0.1 mm" label on the calliper is referring to. Because the vernier scale is in tenths of a millimeter, it corresponds to the next digit of the measurement.

To read the vernier scale, look for the value on the vernier scale that best lines up with any tick on the fixed scale. In this example it is 6. This means the measurement is 2.26 cm or 22.6 mm.


 

Watch the following video demonstration of measuring using a calliper with a vernier scale: