Square kilometre (U.S. spelling: square kilometer), symbol km², is an SI unit of surface area. It is one of the SI derived units.

1 km² is equal to:

• the area of a square measuring 1 kilometre on each side
• 1 000 000 m²
• 100 hectares
• 0.386 102 square miles (statute)
• 247.105 381 acres

Conversely:

• 1 m² = 0.000 001 km²
• 1 hectare = 0.01 km²
• 1 square mile = 2.589 988 km²
• 1 acre = 0.004 047 km²

Note: "km²" means square kilometre and not kilo–square metre. For example, 3 km² is equal to 3 000 000 m², not 3000 m².

Comparative order of magnitude

The 1 E6 m² orders of magnitude page gives comparisons with geographic areas.

hectare (10⁴ m²) < square kilometre < square megametre (10¹² m²)

See also

• Conversion of units.
• SI prefix for the precise meaning of the prefix "k"

Units of area | SI derived units

Vierkante kilometer | Quadratkilometer | Quilometro cuadrau | Квадратен километър | Pêng-hong-kong-lí | Квадратны кілямэтар | Quilòmetre quadrat | Kilometr čtvereční | Kvadratkilometer | Kilómetro cuadrado | Kvadrata kilometro | Kilomètre carré | Četvorni kilometar | Ferkílómetri | Chilometro quadro | קילומטר רבוע | Kilomita ya mraba | Chiliometrum quadratum | Kvadrātkilometrs | Quadratkilometer | Veerkante killemaeter | Négyzetkilométer | Километру пэтрат | Vierkante kilometer | 平方キロメートル | Kilometr kwadratowy | Quilómetro quadrado | Kilometru pătrat | Квадратный километр | Štvorcový kilometer | Kvadratni kilometer | Квадратни километар | Neliökilometri | Kvadratkilometer | Quadrat kilometer | ตารางกิโลเมตร | Kilomete cwåré | 平方千米