square feet

The square foot is an Imperial unit / U.S. customary unit (non-SI non-metric) of area, used in the United States, United Kingdom and elsewhere. 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.

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
• the equation is length times width.

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 slash through it. It is also occasionally written as a square with a vertical line bisecting it. If your browser is up to it, you may see it here: ⏍

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 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 ^[1]

References

1. ^ Das Hauslexikon, vol. VI, Leipzig: Breitkopf und Härtel 1837, p. 596

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

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