SpaceTEC® Resource Blog for Aerospace Technicians


Caliper tools are considered transfer tools because the measurement cannot be read directly.  Caliper tools “make contact with the part (on the dimension being measured), are then locked in the measured position, and are measured with another tool…” such as a rule or micrometer. (Griffith 2003)  With caliper tools being a transfer tool, it doesn’t matter if the part being measured is in English or metric form.  The caliper tool is used to measure the part which then you can compare it to either a English or metric rule or micrometer.

Calipers can be also used as a go/no go tool.  You would preset and lock a caliper against a rule or master part and do a “fit check” on your part to see if a part meets the measurement required.

Though Caliper tools are good for regular measurements they should not be used when accuracy of less than 0.015 ” or 0.39 mm is required. (Krar and Check 1997)

There are two basic types of calipers, outside and inside calipers.


Outside calipers measure the outside surface of a round or flat surface.  The most common type of outside caliper is the spring joint caliper.   To use a outside caliper you would:

1. Measure the part with the caliper and lock it in place.

2. Compare the caliper to a rule to determine the measurement or compare it against a Master Part.









Inside Caliper

Inside Calipers are used to measure the inside diameters of a circular object such as a pipe or to measure the inside width of a slot or keyhole.

Using a inside caliper

1. Hold one leg against the bottom surface of the area your measuring with your finger.

2. Turn the adjusting nut until the second leg touches the opposite side and lock legs in place.

3. Compare the caliper against a rule or Master part, or for more accuracy, use a micrometer on the caliper.



Calipers are easy to use and very simple tools to add precision to your work.  Don’t underestimate a caliper’s usefulness when it comes to your work.

If there are any other common measuring tools or some other aerospace technician subjects you would like to see covered, please feel free to email your suggestion and we will work to cover it here.


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Tuesday, June 14th, 2011 Applied Mechanics, Tests and Measurements