# Square kilometre

**Square kilometre** (International spelling as used by the International Bureau of Weights and Measures) or **square kilometer** (American spelling), symbol **km ^{2}**, is a multiple of the square metre, the SI unit of area or surface area.

1 km^{2} is equal to:

- 1,000,000 square metres (m
^{2}) - 100 hectares (ha)

It is also approximately equal to:

- 0.3861 square miles [2]
- 247.1 acres [3]

Conversely:

- 1 m
^{2}= 0.000001 (10^{−6}) km^{2} - 1 hectare = 0.01 (10
^{−2}) km^{2} - 1 square mile = 2.5899 km
^{2}[4] - 1 acre = about 0.004047 km
^{2}[5]

The symbol "km^{2}" means (km)^{2}, square kilometre or kilometre squared and not k(m^{2}), kilo–square metre. For example, 3 km^{2} is equal to 3×(1,000m)^{2} = 3,000,000 m^{2}, not 3,000 m^{2}.