# Square kilometre

Square kilometre (U.S. spelling: square kilometer), symbol km², is a decimal multiple of the SI unit of surface area, the square metre, one of the SI derived units. 1 km² is equal to:
• 1,000,000 m²
• 100 ha (hectare)
Conversely:
• 1 m² = 0.000 001 (10-6) km²
• 1 hectare = 0.01 (10-2) km²
• 1 square mile = 2.589 988 km²
• 1 acre = 0.004 047 km², 40.47 ha or 4047 m²
Note: "km²" means (km)², square kilometre or kilometre squared, and not k(m²), 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 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).

## Source

Conversion Factors. MINFILE Coding Manual. Ministry of Energy, Mines and Petroleum Resources. Retrieved on 2007-10-13.

 Conversion of units. SI prefix for the precise meaning of the prefix "k" Square Kilometre Array, a proposed radio telescope which is intended to have a collecting area of approximately one square kilometre.
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Si, si, or SI may refer to (all SI unless otherwise stated):

In language:
• One of two Italian words:
• (accented) for "yes"
• si

units of measurement have played a crucial role in human endeavour from early ages up to this day. Disparate systems of measurement used to be very common. Now there is a global standard, the International System (SI) of units, the modern form of the metric system.
Area is the measure of how much exposed area any two dimensional object has. It is expressed in square units, and is calculated by adding together the areas of all the faces of the object.

## Area formulas

Note: For 2D figures, the surface area and the area are the same.
square metre (also spelled meter, see spelling differences) is the SI derived unit of area, with symbol m². It is defined as the area of a square whose sides measure exactly one metre.
SI derived units are part of the SI system of measurement units and are derived from the seven SI base units.

## Dimensionless derived units

The following SI units are actually dimensionless ratios, formed by dividing two identical SI units.
square mile is an imperial and US unit of area equal the area of a square of one statute mile. It should not be confused with the archaic miles square, which refers to the number of miles on each side squared.
square kilometre (U.S. spelling: square kilometer), symbol km², is an SI unit of surface area. It is one of the SI derived units. It is equal to:
• 100 hectares
• 1 E+6 m² or 106
• An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. The ratio most commonly used is 10.
A hectare (symbol ha, pronounced /ˌhɛkˈtɛə(ɹ)/) is a unit of area equal to 10,000 square metres, or one square hectometre, and commonly used for measuring land area.
Conversion of units refers to conversion factors between different units of measurement for the same quantity.

## Techniques

The simplest way to convert from one unit to another is to carry through the units themselves in the mathematical operation.