The 5 Primary Caliper Measurements
There are five primary types of measurements you can perform with a caliper, Inside, Outside, Depth, Step, and Compound. Below we will explain exactly what these measurements are and how to perform them.
Outside measurements are the most basic type of caliper measurement. These measurements can be used for measuring diameter, thickness, or the outside distance between two points. To make this measurement, simply open the outside jaws, place them around your object, then gently close the jaws until they make firm contact with your object. For an accurate measurement, assure the surface is parallel to the jaws. Never force the jaws closed around your object, as soon as there is resistance top your adjustment. If you over tighten the jaws, you run the risk of damaging your caliper and getting an incorrect measurement.
As the name implies, inside measurements can be used to measure the internal dimensions of an object. These are ideal for finding the diameter of a hole, or width of a channel/groove. To take this measurement, close the caliper jaws, and insert them into your object. Just like with the outside measurement, gently open the jaws until you encounter resistance. Since inside measurements can be a little more difficult to line up correctly, double-check that the caliper is making full contact with the intended surface and is not turned at a funny angle.
To make a depth measurement, set your object on a level surface and place the back end of your caliper on top. Make sure you leave enough clearance for the depth gauge is perpendicular to the surface being measured, and that it can descend completely to the level surface or the bottom of the hole. For the best results, we suggest the use of a surface plate as your level surface.
The ability to take a step measurement is an often overlooked feature available on many calipers. To make this measurement, open the caliper slightly and place the top caliper’s back edge, the sliding jaw, on the edge of your upper step. Next, lower the front edge, the fixed jaw, until it makes contact with your lower step. For an illustration, please see the diagram below.
The final type of caliper measurement is the compound measurement. This measurement either involves a combination of two or more of the measurements above and the zero button, for digital calipers or a little bit of math for dial calipers. Compound measurements are commonly used to find center distance, remaining thickness, and comparative measurements. To take a compound measurement, measure your first dimension, before removing the caliper from the object, hit the zero button. With your new zero, take your second measurement. The number that appears on the caliper is the difference between your two measurements. If you are using a dial or vernier caliper, you will have to write down and subtract the measurements to find your difference.