Convert Square Kilometer (km²) to Acre (US Survey) (ac (US)) instantly.
About these units
Square Kilometer (km²)
A square kilometer equals one million square meters and is the standard unit for expressing large land areas, especially in geography, ecology, national planning, and environmental science. Countries, cities, national parks, forests, wetlands, and even ocean surface regions are frequently described in km². Because it provides a manageable scale for features too large for hectares or acres, it is widely used in atlases, scientific papers, and government reports. The square kilometer also plays a major role in ecology, where species ranges, habitat fragmentation, and conservation zones are measured using this unit. In geopolitics, km² help define national borders and territorial claims, making it a powerful instrument of scientific and political discourse.
Acre (US Survey) (ac (US))
The US survey acre is based on the US survey foot, making it slightly different from the international acre. With a value of 43,560 survey-square feet, it appears extensively in historical property records and federal land surveys. Because millions of acres in the United States were mapped using PLSS, the survey acre remains necessary for interpreting legal land rights, even though modern mapping often uses metric units or the international foot. This specialized acre illustrates how subtle unit differences can survive for centuries due to legal and administrative inertia.