Square foot

The square foot is an imperial unit / U.S. customary unit (non-SI non-metric) of area, used mainly in the United States, the United Kingdom, and Canada. It is defined as the area of a square with sides of 1 foot (0.333... yards, 12 inches, or 0.3048 metres) in length. For comparison, the average one-family house in the United States in 2007 had a total floor area of approximately 2500 square feet.^[1]

Symbols

There is no universally agreed symbol but the following are used:

• square feet, square foot, square ft
• sq feet, sq foot, sq ft, SF
• feet/-2, foot/-2, ft/-2
• feet^2, foot^2, ft^2
• feet², foot², ft²

A symbol for square foot, square feet, and "per square foot" commonly used in architecture, real estate and interior space plans is a simple square with a vertical line bisecting it. It is also occasionally written as a square with a slash through it.

Conversions

1 square foot is equivalent to:

• A block 12 inches by 12 inches has a square foot area of 1 square foot. 12 inches is equal to 1 foot.
• 144 square inches
• 1/9 square yards
• 0.01 "squares". (A square is a unit used in roofing to measure the area of a roof and is also a unit used in Australia before metrication (and since) to measure the floor area of a house. 1 "square" = 100 sq ft)
• ≈0.00002295684 acres
• 92 903.04 square millimetres
• 929.0304 square centimetres
• 0.09290304 square metres
• 0.000000092903040 square kilometres

Historical Use

Before metrication, the square foot was in use throughout Europe, as part of the traditional system of measurement, which showed considerable local variation. Some examples below:

• Bavarian square foot = 0.0864751 m²
• Prussian square foot = 0.098504 m²
• Viennese square foot = 0.099921 m²
• Parisian square foot = 0.105521 m² ^[2]

References

See also

• 1 E-1 m² for a comparison with other areas
• Cubic foot
• Orders of magnitude (area)
• Conversion of units
• Area (geometry)
• Square (algebra), square root
• Miscellaneous Technical (Unicode) for a list of miscellaneous technical symbols and fonts which support the square foot symbol