Millimeter vs. Micrometer — What's the Difference?

A unit of length equal to one thousandth (10-3) of a meter, or 0.0394 inch. See Table at measurement.

A micrometer, sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for accurate measurement of components in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, vernier, and digital calipers. Micrometers are usually, but not always, in the form of calipers (opposing ends joined by a frame).

Alternative spelling of millimetre

A gauge that measures small distances or thicknesses between its two faces, one of which can be moved away from or towards the other by turning a screw with a fine thread.

A lineal measure in the metric system, containing the thousandth part of a meter; equal to .03937 of an inch. See 3d Meter.

US spelling of micrometre

A metric unit of length equal to one thousandth of a meter

A device for measuring very small distances, objects, or angles, especially one based on the rotation of a finely threaded screw.

See micron.

A device used to measure distance very precisely but within a limited range, especially depth, thickness, and diameter.

Alternative spelling of micrometre

An instrument, used with a telescope or microscope, for measuring minute distances, or the apparent diameters of objects which subtend minute angles. The measurement given directly is that of the image of the object formed at the focus of the object glass.

Caliper for measuring small distances

A metric unit of length equal to one millionth of a meter