Open the calipers and close the jaws gently on the object
Read the main scale value just to the left of the vernier or digital display
Find the vernier line that lines up exactly with a main scale line
Add the vernier reading to the main scale reading
For digital calipers, read the number shown on the screen
Use the correct unit shown on the caliper
Check whether the reading is in millimeters or inches
Make sure the calipers are zeroed before measuring
Measure the outside, inside, or depth using the appropriate jaws or rod
Keep the calipers straight and aligned with the object
Record the final measurement accurately