CM - Circular Mil Area
The circular mil area (CM) unit denotes the cross-sectional size of a wire or a cable.
The circular mil is a unit of area used especially when denoting the cross-sectional size of a wire or cable.
- A circular mil is the equivalent area of a circle whose diameter is 0.001 (10-3) inch, or approximately 0.7854 millionths of a square inch.
Mils of circular wire or cable can be calculated as:
mils = 1000 d (1)
where
d = diameter of cable or wire (inches)
Example - Calculating Mil
Mils of a 1 inch wire:
mils = 1000 (1 in)
= 1000
Mils of a 1/2 inch wire:
mils = 1000 (1/2 in)
= 500
The Circular Mil
The circular mil area of a wire or cable is equal to its diameter - expressed in mils squared:
CM = mil2 (2)
where
CM = circular mil area (CM)
The diameter in mil of a circular wire can be expressed as:
mil = CM1/2 (2b)
Example - Calculating mil area
The mil area of an 3/8 in wire (0.375 in or 375 mil) can be calculated as
CM = (375 mils) (375 mils)
= 140625 cmil
Example - Calculating mil
The mil of an circular wire with area 140625 CM can be calculated as
mil = 1406251/2
= 375 mils
The Square Mil Area
The square mil is the area of a square whose sides are one mil, or 1 x 10-3 inch, and can be expressed as:
One Square Mil = (1 x 10-3)2
= 1 x 10-6 in2
Converting Circular Mil to Square Inch
- 1 Circular mil = 0.7854 x 10-6 Square Inch
Converting Circular Mil to Square Mil
- 1 Circular Mil = 0.7854 Square Mil
- 1 Square Mil = 1.27 Circular Mils
Converting Circular Mil to metric units
- 1 circular mil = 5.066 x 10-10 m2 = 5.066 x 10-6 cm2
- 1 m2 = 1.974 x 109 circular mil
- 1 cm2 = 1.974 x 105 circular mil