The square centimeter (cm²) is a metric area unit equal to one ten-thousandth of a square meter, commonly used in medical reports, lab measurements, and small product specifications. Skin lesion sizes, fabric swatches, and circuit board components are often measured in square centimeters. One square centimeter equals exactly 0.155 square inches.

The square inch (in²) is a small imperial area unit equal to a square measuring one inch on each side, commonly used in engineering specifications, screen size descriptions, and pressure measurements. Piston areas, material stress calculations, and electronic component sizes are frequently expressed in square inches. One square inch equals exactly 6.4516 square centimeters.