Square mil

A square mil is a unit of area, equal to the area of a square with sides of length one mil. A mil is one thousandth of an international inch. This unit of area is usually used in specifying the area of the cross section of a wire or cable.

Equivalence to other units of area
1 square mil is equal to:
 * 1 millionth of a square inch (1 square inch is equal to 1 million square mils)
 * 1e-6 in2
 * about 1.273 circular mils (1 circular mil is equal to about 0.7854 square mils). 1.273 ≈ $in2$ and 0.7854 ≈ $4⁄\pi$.