A square inch (sq in or in²) is a unit of area commonly used in the United States and other countries that use the imperial system of measurements. It is defined as the area of a square with sides that each measure one inch in length.
In terms of square centimeters, one square inch is approximately equal to 6.4516 square centimeters (cm²).
Square inches are used in various applications, especially for measuring small areas, such as the size of a sheet of paper, the dimensions of electronic devices, or the area of specific objects or surfaces in everyday life.
A square perch, often referred to as a "square pole" or simply "perch," is an obsolete unit of land area measurement. It was historically used in some English-speaking countries, including the United States and the United Kingdom, for land surveying and property descriptions.
One square perch is equivalent to one square rod or one square pole. In terms of modern measurements, one square perch is approximately equal to 25.29285264 square meters (m²) or 0.00625 acres.
Like other obsolete units of land area measurement, the square perch has largely been replaced by more standardized systems of measurement, such as square meters and square feet, in modern times. It is rarely encountered in contemporary land transactions or legal documents.