Convert Circular Mils to Square Chains
Convert Circular Mils (cmil) to Square Chains (ch²) instantly and accurately.
Conversion Formula
ch² = cmil × 1.252101449e-12
About Circular Mils
A circular mil (cmil) is a unit used in electrical engineering to specify the cross-sectional area of round wires and cables. Equal to the area of a circle with a diameter of exactly one thou (one thousandth of an inch) - approximately 5.067 × 10⁻¹⁰ m² - it simplifies wire calculations: the cross-sectional area in cmil equals the wire diameter in mils, squared. US electrical codes (NEC/NEMA) specify conductor sizes in circular mils, and large cables are rated in thousands of circular mils (kcmil or MCM). A 12 AWG wire, common in US household wiring, has a cross-section of 6,530 cmil.
About Square Chains
A square chain (ch²) is a surveying unit equal to the area of a square with sides of one Gunter's chain (66 feet or ~20.12 m), approximately 404.69 m². Ten square chains equal exactly one acre, making it the natural subdivision unit in traditional land surveying. The US Public Land Survey System used chains to lay out townships and sections, and square chains appear throughout old legal property descriptions and government land grants across North America. One square chain equals exactly 16 square rods.
Quick Reference Table
| Circular Mils (cmil) | Square Chains (ch²) |
|---|---|
| 1 cmil | 1.252 × 10-12 ch² |
| 2 cmil | 2.504 × 10-12 ch² |
| 5 cmil | 6.261 × 10-12 ch² |
| 10 cmil | 1.252 × 10-11 ch² |
| 25 cmil | 3.13 × 10-11 ch² |
| 50 cmil | 6.261 × 10-11 ch² |
| 100 cmil | 1.252 × 10-10 ch² |