Thousandth of an inch

Thousandth of an inch
ID-1 cards like payment cards have a thickness of 0.03 inches (30 thou).
General information
Unit system	Imperial/US units
Unit of	Length
Symbol	thou, mil
Conversions
1 thou in ...	... is equal to ...
imperial/US units	0.001 in
SI units	25.4 μm

A thousandth of an inch is a derived unit of length in a system of units using inches. Equal to 1⁄1000 of an inch, a thousandth is commonly called a thou /ˈθaʊ/ (used for both singular and plural) or, particularly in North America, a mil (plural mils).

The words are shortened forms of the English and Latin words for "thousand" (mille in Latin). In international engineering contexts, confusion can arise because mil is a formal unit name in North America but mil or mill is also a common colloquial clipped form of millimetre.^[1] The units are considerably different: a millimetre is approximately 39 mils.