AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

All About Micrometers and Their Different Types

A micrometer is an instrument used for making very fine measurements of dimensions such as length and diameter. Micrometers typically consist of a C-shaped frame with a moveable jaw that is operated by an integral screw. Metric micrometers in particular, generally measure in 0.01mm increments and imperial versions in 0.001 inches. Due to their size and design, micrometers can provide much more accurate measurements than other devices, such as dial or vernier calipers but this is highly dependent on the user’s care.

Working Principles

Micrometers work on the basic operating principle used by a screw and a nut. Within a micrometer, a screw is attached to a barrel-like structure, called the thimble, which is used to measure the distance of an object. In an external micrometer, when you turn the threaded screw and thimble, it will slowly close the gap of a clamp until the jaws are tight against the object being measured. Once you have fully clamped the jaws around an object, the degree to which you have turned the screw will be conveyed on the thimble, or a digital display screen, as an accurate measurement of the distance between the two sides of the C-shaped jaws. Internal micrometers work on the same principle but with a different shape, which will be further explained in the next section.

Types of Micrometers

While there are many different types of micrometers, each of them can be divided into three major categories: internal micrometers, external micrometers, and depth micrometers. External micrometers work as described above, with an adjustable jaw that clamp inwards around the exterior of an object. Conversely, internal micrometers expand outwards to find the distance between the inner surfaces of an object. Lastly, depth micrometers are used to measure the depths of holes, slots, or steps, and they come with a variety of interchangeable rods of differing lengths, so that they can be used to measure a range of depths. Nonetheless, each of these micrometer categories can have either a digital or analog display. Whereas analog micrometers show the measurement as an engraved mark on the thimble, digital micrometers can give a highly accurate measurement that is calculated based on the degree to which the screw was turned.

Common Applications

The ability to make very precise measurements has made micrometers a commonly used tool in various industries. One such application is to measure machine and moving parts. For example, parts that move in and out of each other, such as pistons, in order to remain in a straight, steady line. Otherwise, even the smallest misalignment could cause faults or unnecessary wear on the machine. Bearings and pipe fitting also need precise measurements to function correctly. Finally, micrometers are also a preferred choice for measuring the minute thickness of items such as sheet metals where the dimensions need to be exact.


Micrometers are indispensable tools for making very precise measurements at miniscule dimensions. As such, they are effective instruments for ensuring the proper fit of machinery, and for meeting strict industrial regulations of width, length, and depth. If you are interested in buying a micrometer for your operations, or other related industrial components, you can rely on Stacked NSN for a wide inventory of components that are new, used, obsolete, and hard-to-find. Backed by rapid lead times and a widespread supply network, we are well-equipped to handle all your operational requirements, even for AOG situations. Call or use our Instant RFQ service today to start procuring the parts you require with unbeatable time and cost savings, when you partner with Stacked NSN!


June 25, 2024


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