A square foot (ft²) is a unit of area that equals the area of a square with sides measuring one foot. It is part of the imperial and US customary systems, not an SI unit.
The concept of the square foot dates back to ancient civilizations, where land measurement was vital for agriculture. The unit became more standardized in the 19th century with the rise of real estate and construction industries. The term "foot" itself originates from the average human foot length.
Square feet are commonly used in real estate to measure the area of homes, apartments, and commercial spaces. It is also used in construction, landscaping, and interior design to calculate materials needed, such as flooring or paint. Predominantly used in the United States and a few other countries, it contrasts with square meters (m²) used in most of the world.