Square Kilometers
Abbreviation/Symbol:
km²
(km)2
sq km
Unit of:
Worldwide use:
A square kilometer (km²) is 1,000,000 square meters, or 100 hectares. It is 0.386 square miles.
Countries, cities and lakes are sized in square kilometers. A square kilometer is 1,000m by 1,000m, not 1,000 square meters, so the factor to square meters is a million.
Definition:
A square kilometer (km²) is the area of a square measuring one kilometer on each side, which is 1,000 meters by 1,000 meters. That makes 1,000,000 square meters, or 100 hectares.
Square kilometers are the unit for countries and oceans: Australia is about 7.7 million km², the sixth-largest country, and the Pacific Ocean about 165 million km², the largest ocean.
Origin:
A square kilometer is 1,000,000 square meters, or 100 hectares. It has no history of its own: it is simply the kilometer squared, 1,000 meters by 1,000 meters.
The square kilometer, or km², is derived from the kilometer by squaring its length. It represents the area of a square with sides measuring one kilometer each. The kilometer, a unit of length in the metric system, was first introduced during the French Revolution in the late 18th century. It was defined as one ten-thousandth of the distance from the North Pole to the equator along a meridian passing through Paris.
Common references:
Total square kilometers of the surface of the earth = 510 million sq km
Total square kilometers of the earth's oceans = 362 million sq km
Usage context:
Countries, regions and lakes are measured in square kilometers (km²), and population density is quoted per km² too. One km² is 100 hectares, or about 0.386 square miles.
Square kilometers are also frequently used in environmental studies and conservation efforts. Scientists and researchers utilize this unit to measure the extent of forests, wetlands, and other natural habitats. By quantifying the size of these areas, they can assess the biodiversity, monitor changes over time, and develop strategies for their preservation.
Individual fields are usually given in hectares, so square kilometers only come in for land use on a regional or national scale. For anyone thinking in acres, 1 km² is about 247 acres.