a 6 μm diameter carbon filament above a 50 μm diameter human hair
|1 μm in ...||... is equal to ...|
| si units|| 1×10−6 m|
| natural units|| 6.1877×1028 ℓp|
| imperial/us units|| 3.2808×10−6 |
the micrometre (international spelling as used by the international bureau of weights and measures; si symbol: μm) or micrometer (american spelling), also commonly known by the previous deprecated name 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 0.000039 inch).
the next smallest common si unit is the nanometer, equivalent to one one-thousandth of a micrometer, 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, and for grading wool by the diameter of the fibres. the width of a single human hair ranges from approximately 20 to 200 μm. the longest human chromosome is approximately 10 μm in length.