Square mil
Encyclopedia
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.
) size is as follows. An represents the Square Mil Area for the AWG size n.
which is essentially a πr2 formula where we divide the mils diameter by 2 to obtain the radius r; or
or
Sizes with multiple zeros are successively larger than the Number 0 gauge size and can be denoted using "number of zeros/0"; for example 4/0 for the number 0000 gauge. For an m/0 AWG wire size, use
n = −(m−1) = 1−m in the above formula.
Units of measurement
A unit of measurement is a definite magnitude of a physical quantity, defined and adopted by convention and/or by law, that is used as a standard for measurement of the same physical quantity. Any other value of the physical quantity can be expressed as a simple multiple of the unit of...
of area
Area
Area is a quantity that expresses the extent of a two-dimensional surface or shape in the plane. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat...
, equal to the area of a square with sides of length one mil
Thou (unit of length)
A thou also known as a mil or point, is the verbalized abbreviation for "thousandth of an inch." It is a unit of length equal to 0.001 inch....
. A mil is one thousandth of an international inch
Inch
An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...
. This unit of area is usually used in specifying the area
Area of a circle
The area of a circle is πr2 when the circle has radius r. Here the symbol π denotes, as usual, the constant ratio of the circumference of a circle to its diameter...
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)
- 6.4516 E-10 square metreMetreThe metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...
s - about 1.273 circular milCircular milA circular mil is a unit of area, equal to the area of a circle with a diameter of one mil . It is a convenient unit for referring to the area of a wire with a circular cross section, because the area in circular mils can be calculated without reference to pi .The area in circular mils, A, of a...
s (1 circular mil is equal to about 0.7854 square mils)
- Square Mils = π/4 × Circular Mils
AWG Square Mil Formula
The formula to calculate the Square Mil for any given AWG (American Wire GaugeAmerican wire gauge
American wire gauge , also known as the Brown & Sharpe wire gauge, is a standardized wire gauge system used since 1857 predominantly in the United States and Canada for the diameters of round, solid, nonferrous, electrically conducting wire...
) size is as follows. An represents the Square Mil Area for the AWG size n.
which is essentially a πr2 formula where we divide the mils diameter by 2 to obtain the radius r; or
or
- For example, a number 12 gauge wire would use n = 12; and the calculated result would be 5128.608215 Square Mils
Sizes with multiple zeros are successively larger than the Number 0 gauge size and can be denoted using "number of zeros/0"; for example 4/0 for the number 0000 gauge. For an m/0 AWG wire size, use
n = −(m−1) = 1−m in the above formula.
- For example, the number 0000 gauge or 4/0 gauge, would use n = −3; and the calculated result would be 166190.2514 Square Mils
See also
- Mil (unit of length)
- Circular milCircular milA circular mil is a unit of area, equal to the area of a circle with a diameter of one mil . It is a convenient unit for referring to the area of a wire with a circular cross section, because the area in circular mils can be calculated without reference to pi .The area in circular mils, A, of a...
- Area of a circleArea of a circleThe area of a circle is πr2 when the circle has radius r. Here the symbol π denotes, as usual, the constant ratio of the circumference of a circle to its diameter...