A circular mil (often abbreviated as cmil or kcmil) is a unit of area used primarily in the United States for measuring the cross-sectional area of a round wire or cable. It is a convenient unit for specifying the size of electrical conductors.
One circular mil is equal to the area of a circle with a diameter of one mil (1/1000th of an inch) or approximately 0.000000506707 square inches (in²). In metric units, one circular mil is approximately equal to 0.000001273 square millimeters (mm²).
Circular mils are commonly used in the American Wire Gauge (AWG) system to specify wire sizes. The AWG system assigns a unique number to each wire size, and this number is related to the wire's cross-sectional area in circular mils. For example, a larger AWG number corresponds to a smaller wire size with fewer circular mils, while a smaller AWG number corresponds to a larger wire size with more circular mils. This system allows for easy reference and selection of wire sizes for various electrical applications.
A square decimeter (often abbreviated as dm²) is a unit of area in the International System of Units (SI). It represents a square with sides that each measure 1 decimeter (10 centimeters) in length.
One square decimeter is equal to 0.01 square meters (m²) because each side of the square is 10 centimeters long, and when you square that length, you get 0.01 square meters.
To put it in perspective, a square decimeter is a relatively small unit of area. It is often used for measuring small areas, such as the surface area of small objects, pieces of paper, or the dimensions of certain materials in scientific and technical contexts.