How to Read a Dial Caliper

Dial caliper is a handy and versatile measuring tool. It can measure I.D, O.D, Step and depth.
Parts of a dial caliper

Clean the measuring faces before and after measurement.Close the jaws and check that the indicator points to “0” on the dial face.If caliper doesn’t zero, loosen the bezel clamp screw and rotate the bezel to the “0” position.Tighten the bezel clamp screw to fix the “0” position.
Dial graduation of .001″and .100″in one revolution for dial caliper of inch system.

Dial graduation of 0.02mm or 0.01mm and 2mm or 1mm in one revolution for dial caliper of metric system.

For example, a measurement of 15.43 millimetres would be obtained by reading 15mm on the main scale, and then adding 0.43mm as determined by the dial(as shown in the image).
Inch Dial calipers are read in a similar fashion.
Note: When using either a metric or inch dial caliper, smaller readings than those graduated may of course be obtained by visual interpolation between graduations.