Archives July/August 2009 : Question and Answer

Q: How do you read a Vernier Caliper?

A: One of the most difficult parts of using a Vernier Caliper is reading it accurately. Before I explain how to do this, let me go over the parts of the Caliper first.


1. Outside jaws: used to measure external diameter or width of an object
2. Inside jaws: used to measure internal diameter of an object
3. Depth probe: used to measure depths of an object or a hole
4. Main scale: gives measurements of up to one decimal place(in cm).
5. Main scale: gives measurements in fraction(in inch)
6. Vernier gives measurements up to two decimal places(in cm)
7. Vernier gives measurements in fraction(in inch)
8. Retainer: used to block movable part to allow the easy transferring a measurement

Ok, now you know the parts of the caliper...so how do I use it?!


First, find open the caliper and close down the outside jaws onto the item to be measured. Make sure the item side are on the same plane as the caliper, if it lays in wonky your measurement will be off.

Second, look for where the 0 mark of the sliding vernier scale lines up on the fixed main scale. In this case, it is before the 2.4 cm mark. So, the first reading is 2.4
cm.

Next, find the mark on the vernier scale that most closely lines up with one of the marks on the main scale. Here, 6.5 and 7.5 are very close, but 9.0 lines up exactly with one of the marks on the fixed scale. This value is the number of
hundredths of centimeters (or tenths of millimeters). So, the second reading is 0.070 cm.

Finally, add the two values together to get the total reading: 2.4 cm + 0.070 cm = 2.470 cm.