Close the jaws gently and check that the zero mark aligns
Open the jaws and place the object between them
Read the main scale value just before the vernier zero
Find the vernier line that exactly matches a main scale line
Multiply the matching vernier line number by the least count
Add the vernier reading to the main scale reading
Include the main scale unit shown on the caliper
Read the depth rod or inside jaws the same way if needed
Record the final value with the correct unit