How do you convert inches to microns?
Multiply by 25,400. An inch is exactly 25.4 mm and each millimetre is 1,000 microns, so there's no rounding anywhere in this one.
Engineers often start from the thou, a thousandth of an inch, which is 25.4 microns. A 0.004 inch feeler gauge is therefore 101.6 microns. Cling film is about 10 to 12 microns thick, or roughly 0.0004 in.
What is an inch?
An inch is a length unit normally used in the United States and, occasionally, in the United Kingdom. It is defined as a twelth (1/12th) of a foot. The inch is normally subdivided into fractions of an inch such as the ½, ¼ and ⅛.
An inch was originally the width of a man's thumb. It is still the everyday length unit in the United States, and TV and computer screens are sold by their size in inches worldwide.
Inches are used in combination with other units of imperial measurement such as feet and yards. For example, a standard door in the United States a football field is 100 yards long or 300 feet or 3,600 inches.
What is a micron?
A micron is one millionth of a meter, or 0.000001 meters. Its symbol is µm, the Greek letter mu followed by m.
'Micron' is the older name for the micrometer, and the SI dropped it in 1967. It survives on filter ratings anyway – a 5 micron filter catches particles down to about 5 micrometers.