Square kilometre

Square kilometre (U.S. spelling: square kilometer), symbol km², is a decimal multiple of SI unit of surface area square metre, 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 * (1,000 m)² = 3,000,000 m², not 3,000 m².

Comparative order

The 10⁶ m² orders of magnitude page gives comparisons with geographic areas.

A hectare (10⁴ m²) is less than a square kilometre which is less than a square megametre (10¹² m²)..