Convert Square Perch (perch²) to Circular Mil (circ mil) instantly.
About these units
Square Perch (perch²)
A square perch is equivalent to a square rod, as "perch" was another historical name for a rod, used in various medieval and regional English measurement systems. Perches commonly appeared in church records, tithing assessments, and agricultural inventories. Because the perch was both a length and an area unit, it played dual roles in land taxation and construction. These overlapping terminologies—rod, pole, perch—reflect the organic evolution of measurement in medieval Europe, long before unified systems took hold.
Circular Mil (circ mil)
A circular mil is defined as the area of a circle with a diameter of exactly one mil. Because wires and cables have circular cross-sections, the circular mil has become a standard unit in electrical engineering for specifying conductor sizes. One circular mil simplifies calculations because area scales directly with the square of wire diameter without needing π in computations. For example, doubling a wire's diameter increases its circular-mil area fourfold. This makes circular mils extremely convenient for determining ampacity, resistance, and voltage drop in electrical conductors. Even though SI units are common elsewhere, the circular mil remains entrenched in North American electrical codes.