Square foot

A square foot is the area of a square that measures one foot on each side. It equals 144 square inches, or about 0.0929 square meters.

In the United States, home size is almost always stated in square feet, and gross living area on an appraisal is reported in whole square feet. ANSI Z765 has measurements taken to the nearest inch or tenth of a foot, with the final area rounded once, at the end.

The unit says nothing about what was measured. The same house can be described as 1,800 square feet or 2,600 square feet depending on whether the basement and garage are included, which is why the measuring standard matters more than the number.

Further reading: Square foot on Wikipedia.