The square millimeter (mm²) is a metric unit of area equal to one-millionth of a square meter, used in precision engineering, microelectronics, and medical imaging. It is ideal for measuring the cross-sectional area of wires, the surface area of microchips, and other tiny surfaces. One square millimeter equals roughly 0.00155 square inches.

The square foot (ft²) is an imperial area unit equal to a square measuring one foot on each side, the standard measurement for home sizes, office space, and rental properties in the United States. Real estate listings in America almost always quote living space in square feet, making it one of the most practically relevant area units. One square foot equals exactly 0.0929 square meters.