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.

square mil
Unit system	Imperial and US customary measurement systems
Unit of	Area
Symbol	mil2
Conversions
1 mil2 in ...	... is equal to ...
Imperial and US customary	10−6 in2
SI units	6.45160×10−4 mm2

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)
• 6.4516×10⁻¹⁰ square metres
• about 1.273 circular mils (1 circular mil is equal to about 0.7854 square mils). 1.273 ≈ ⁠4/π ⁠ and 0.7854 ≈ ⁠π/4⁠.

See also

• Circular mil
• Area of a circle