Micrometre

The micrometre (international spelling as used by the International Bureau of Weights and Measures;[1] SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is an SI derived unit of length equalling 1×10−6 metre (SI standard prefix "micro-" = 10−6); that is, one millionth of a metre (or one thousandth of a millimetre, 0.001 mm, or about 0.00004 inch).[1]

"Micron" redirects here. For other uses, see Micron (disambiguation).
"Microscale" redirects here. For other uses, see Microscale (disambiguation).
For the measuring instrument, see Micrometer (device). For the unit of molar concentration, μM (micromolar), see Molar concentration.

Micrometre
A 6 μm diameter carbon filament above a 50 μm diameter human hair
General information
Unit systemmetric
Unit oflength
Symbolμm
Conversions
1 μm in ...... is equal to ...
   SI units   10−6 m
   Natural units   1.8897×104 a0
   imperial/US units   3.2808×10−6 ft, 3.9370×10−5 in

The nearest smaller common SI unit is the nanometre, equivalent to one one-thousandth of a micrometre, or one billionth of a metre (0.000000001 m).

The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria,[1] and for grading wool by the diameter of the fibres.[2] The width of a single human hair ranges from approximately 20 to 200 μm. The longest human chromosome, chromosome 1, is approximately 10 μm in length.

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