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Home > Education > Vernier Caliper Information

How to read a vernier caliper?

Once the vernier is positioned to make a reading, make a note of where the first mark on the auxiliary scale falls on the main scale. If the object's length is between 1.2 cm and 1.3 cm because the first auxiliary mark is between these two values on the main scale. The last digit (tenths of a millimeter) is found by noting which line on the auxiliary scale coincides with a mark on the main scale. Tthe last digit is 3 because the third auxiliary mark lines up with a mark on the main scale. Therefore, the length of the object is 1.23 cm.

Clean jaws and track of dirt, grease and foreign matter. Verify that gear moves across tracks freely. Bring jaws together and note reading (dial should be reading zero, also if dial is not reading zero, move the dial face to zero set and continue with checks).

On the #1 check (OD jaws) insert a .500-inch (12.7 mm) gauge block between the jaws of the caliper and close so both jaws are touching the gauge block. Record reading.

Repeat steps with a 1-inch (25.4 mm) gauge block and 4-inch (101.6 mm) gauge block. Record reading.

Repeat using appropriate size micrometer standard (150, 200 or 300).

On the #2 check (ID Jaws) set the calipers on 12.7mm and lock into place and measure the jaw width with another pair of calipers that have been calibrated (caliper number must be recorded for traceability). Record reading.

Repeat step for 25.4 mm and 101.6 mm and appropriate length of caliper (150, 200 or 300). Record readings.

On the #3 check (height check) set 12.7 mm gauge block on surface plate, extend the caliper above the block and bring down to touch the block. Record reading.

Repeat step for 25.4 and 101.6mm gauge blocks. Place appropriate size micrometer standard on surface plate and extend the caliper above it and bring the caliper down to touch. Record readings.

Maintain readings on file in the Quality Department.


﹒The last numbered division on the bar to the left of the vernier scale represents millimeters multiplied by 10.
﹒Note how many full graduations are showing between this numbered division and the zero on the vernier scale . Multiply this number by 1 mm.
﹒Find the line on the vernier scale which coincides with a line on the bar. Multiply this number by0.02 mm.
In Fig.6-6 the reading would be as follows: The large? graduation on bar 4×10=40
3 full lines past ? graduation 3×1=3
The 9th line n vernier scale coincides with a line on bar 9×0.02=0.18
Total reading=43.18mm