Square Inch [in2] to Square Millimeter [mm2] Converter

Definition: A square inch (in²) is a unit of area equal to the area of a square that is 1 inch on each side. It is commonly used in the United States and other countries that use the imperial system.

History/origin: The square inch is derived from the inch, which has ancient origins and was traditionally based on the width of a human thumb. Its exact definition has varied throughout history.

Current use: Square inches are used to measure smaller areas, such as the surface area of objects, screens, or printed materials. It's a common unit in manufacturing, design, and everyday measurements in the US.

Definition: A square millimeter (mm²) is a unit of area in the metric system. It is the area of a square with sides that are one millimeter in length. It is equal to one millionth of a square meter.

History/origin: The square millimeter is derived from the millimeter, which is a decimal fraction of the meter, the SI base unit of length. As a unit of area, it follows the same historical development as the meter.

Current use: Square millimeters are used for measuring very small areas, such as the cross-sectional area of wires, thin films, or small electronic components. They are common in scientific research, engineering, and manufacturing where precise measurement of small areas is required.