Convert Square Chain (ch²) to Square Mil (mil²) instantly.
About these units
Square Chain (ch²)
A square chain equals the area of a square one chain (~66 feet) per side, resulting in 4,356 square feet, or exactly 1/10 of an acre. This unit is closely linked to the chain, a surveyor's unit standardized by Edmund Gunter in the 17th century. Because 10 square chains make an acre, survey calculations for early colonial and American lands were extremely efficient. Square chains allowed surveyors to map and divide land rapidly using ropes or metal chains, producing a legacy seen in long, straight property lines still visible today across rural landscapes.
Square Mil (mil²)
A square mil equals the area of a square one mil (0.001 inch) on each side, producing an area of one-millionth of a square inch. This tiny unit appears in microfabrication, thin-film manufacturing, and fine electronic component design. Engineers rely on mils and mil² for PCB trace design, wire bonding pads, and micro-mechanical parts. Despite modern efforts to shift toward metric units, mils remain deeply embedded in American electronics manufacturing due to legacy tooling and engineering standards.