# Circular inch conversions

The circular inch conversion selector selects the area/surface measurement unit to convert to starting from circular inches (circ in). To make a conversion starting from a unit of area other than circular inch, simply click on the "Reset" button.

## About circular inch

The **circular inch** is a unit of area in the Imperial and US customary systems of units equal to 5.067075 × 10^{-4} square meters (1 circular inch = 5.067075 × 10^{-4} m^{2}), the standard derived unit of area in the International System of Units (SI).

The circular inch (circ in) is also equal to 5.067075 square centimeters (cm^{2}), or 506.7075 square millimeters (mm^{2}), or 506.707.5 × 10^{6} square micrometers (μm^{2}) or 5.067075 × 10^{14} square nanometers (nm^{2}) (units of area in the SI), or about 785,398.196 square mils, or 0.785398196 square inches (sq in) or 0.00545415414 square feet (sq ft), which are Imperial / US customary units of area.

The circular inch (circ in) is an Imperial / US customary unit of area. The inch (in) is a unit of length in the Imperial and US customary systems of units. An area of 1.0 circular inch is the area of a circle that is 1.0 inch in diameter.

The conversion formula between square inches and circular inches:

Square Inches = π/4 × Circular Inches

The circular inch is used to specify the area of the cross section of a cable or wire.

Symbol: circ in

Plural: circular inches