There are a few steps for using digital calipers. Always reset best digital calipers to zero as soon as you turn on and remember to start from zero every time. There are 4 ways of measuring
External dimension- To measure an accurate outside dimension, you should position the inside of the jaws parallel to the object, and to measure thickness, you should position the inside of the jaw perpendicular to the objects.
Internal dimension- To measure an accurate internal dimension, you should position the outside of the jaws perpendicular to the object.
Depth Measurement- To measure accurate depth, engage the depth gauge and position the caliper perpendicular to the surface that you want to measure.
Step Measurement- Use the step gauge to measure the distance between one edge to edge above it.
NOTE- Follow the steps because not following the right step can cause incorrect measurement.