Square kilometre, symbol km^{2}, is a decimal multiple of the SI unit of surface area, the square metre, one of the SI derived units. 1 km^{2} is equal to:
Conversely:
Note: "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}.
The 10^{6} m^{2} orders of magnitude page gives comparisons with geographic areas.
A hectare (10^{4} m^{2}) is less than a square kilometre which is less than a square megametre (10^{12} m^{2}).
The ISO symbol "km²" means "square kilometres" (not to be confused with "kilometres squared"). One of them contains 100 ha (hectares) and/or 1 million square metres (m²) and is a little over twice the size of Vatican City, just over half the size of Monaco (country ranked 192nd by area), and onethird of the size of the City of London.
The Imperial unit "square mile" contains approximately 2.5900 km².
