Reading the Vernier Caliper

The vernier caliper is a device used to measure linear dimensions, and is shown below. It is actually quite simple to use.

There is a fixed main scale, graduated the same as a meter stick. A movable vernier scale rides along the main scale, subdividing each mm of the main scale. Since this is a 20-division caliper, the subdivision is 1mm/20 = 0.05mm. Measurements are made relative to the index - the first line on the vernier scale labeled 0.

First, see where the index hits the main scale. Here, it is between 20mm and 21mm. Therefore, this measurement is 20.something mm.

Next, look for which graduation of the vernier scale aligns with a graduation on the main scale (there will be only one). Moving to the right along the vernier scale from the index, the graduations are 0.05mm, 0.10mm, 0.15mm, 0.20mm 0.25mm, 0.30mm, 0.35mm, 0.40mm, 0.45mm, 0.50mm, 0.55mm, 0.60mm, 0.65mm, 0.70mm, 0.75mm, 0.80mm, 0.85mm, 0.90mm, 0.95mm, and 0.00mm (0). The values in bold correspond the the numbers on the vernier scale. As you can see, the 13th, or 0.65mm graduation (three past the 50) is the one which aligns. The measurement is then 20.65mm, or 2.065cm.

Virtual Vernier Caliper Simulator

Example

89mm + 0.10mm (2nd graduation aligns) = 89.10mm (8.910cm). 

Example

40mm + 0.00mm (index and final 0 align) = 40.00mm (4.000cm). 

Example

Note the different calibrations on this caliper. On the main scale, there is 10(mm), 20(mm), ... instead of 1(cm), 2(cm), ... Also, the graduations on the vernier scale are 0.05mm, 0.10mm, 0.15mm, 0.20mm 0.25mm, 0.30mm, 0.35mm, 0.40mm, 0.45mm, 0.50mm, 0.55mm, 0.60mm, 0.65mm, 0.70mm, 0.75mm, 0.80mm, 0.85mm, 0.90mm, 0.95mm, and 0.00mm (10).

44mm + 0.70mm (14th graduation aligns) = 44.70mm (4.470cm).