A micrometre is smaller than a millimetre on the metric scale. Micrometers are also known as microns, and a millimetre is made up of 1,000 microns. A human hair is 40 to 50 microns broad (0.04 millimetre), while a dust mite is 400 microns long (0.44 millimetre).
The metre is the base unit in the metric system, and other units are multiplied or divided by powers of ten to represent them. The micron (1 x 10-6 m), nanoscale (1 x 10-9 m), picometer (1 x 10-12 m), and femtometer (1 x 10-15 m) are smaller units than the millimetre.
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