Square kilometre

The square kilometre (square kilometer in American spelling; symbol: km²) is a multiple of the square metre, the SI unit of area or surface area. In the SI unit of area (m²), 1 km² is equal to 1M(m²).

1 km² is equal to:

• 1,000,000 square metres (m²)
• 100 hectares (ha)

It is also approximately equal to:

• 0.3861 square miles
• 247.1 acres

Conversely:

• 1 m² = 0.000001 (10⁻⁶) km²
• 1 hectare = 0.01 (10⁻²) km²
• 1 square mile = 2.5899 km²
• 1 acre = about 0.004047 km²

The symbol "km²" means (km)², square kilometre and not k(m²), kilo–square metre. For example, 3 km² is equal to 3×(1,000m)² = 3,000,000 m², not 3,000 m².