Convert Square Mile (US Survey) (mi² (US)) to Circular Mil (circ mil) instantly.
About these units
Square Mile (US Survey) (mi² (US))
The US survey square mile is extremely close to the international square mile but is defined using the US survey foot, a slightly different value than the international foot historically used in land surveying. This unit appears in American land deeds, cadastral maps, and federal land management documents. The Public Land Survey System (PLSS), which divided much of the western United States into townships and sections, relied heavily on survey-based square miles. Although the modern US has transitioned to the international foot (as of 2023), historical land descriptions remain legally tied to the survey-based definition, ensuring its continued relevance.
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.