What’s a Micrometer?

Print anything with Printful

Micrometers are precise measuring instruments used in engineering and mechanical tasks. They come in different types, including outside, inside, and depth micrometers, each with a specific purpose. Micrometers can measure dimensions down to 0.001 inch or 0.01 millimeter, and some have a built-in vernier scale for even greater accuracy.

A micrometer, often called simply a micrometer or microphone, is a finely calibrated measuring instrument. Micrometers are routinely used in engineering and mechanical tasks to accurately measure small distances or dimensions. Micrometers come in different configurations, but they all rely on the same basic mechanism to take measurements. The measuring tip, or spindle, is moved a specific distance by turning a fine-thread calibrated screw. When the spindle touches the object to be measured, the dimension can be read on a dial or digital readhead.

Micrometers vary in design, depending on the task they are intended for. There are many specialized types of micrometers, but the three most common types are the outside micrometer, inside micrometer, and depth micrometer. As the names suggest, each style of micrometer has its specific purpose.

The most familiar type of micrometer is the outside micrometer. This tool is sometimes called a caliper micrometer because it usually has a “C” gauge or body and a spindle that moves up or down as you turn the screw. The outside micrometer is often used to measure the thickness or length of an object or the diameter of a round or spherical object.

An inside micrometer can also have a caliper design, but is also available with a straight body. Instead of a spindle, the internal micrometer uses measuring pads or points. These face outward and extend towards the object being measured as you turn the screw. This design makes the inside micrometer perfect for accurately measuring the inside diameter of a bore or other opening.

The depth micrometer usually has a straight body design. This type of micrometer is often sold as a set, with interchangeable steel rods of various lengths. Adding an appropriate length rod to the depth gauge spindle allows the user to measure the distance to the bottom of a hole or groove. In some cases, a depth micrometer can also be adapted to measure the height of a part, such as a shim or spacer.

Regardless of style, inch graduation micrometers can easily show readings down to 0.001 inch and metric micrometers typically show 0.01 millimeter increments. For even greater accuracy, some micrometers have a built-in vernier scale. The Vernier scale offers users ten additional gradations to further pinpoint their size. A micrometer equipped with a Vernier can take measurements down to 0.0001 inch or 0.001 millimeter.

Protect your devices with Threat Protection by NordVPN

Skip to content