Convert Barn (b (area)) to Square Kilometer (km²) instantly.
About these units
Barn (b (area))
The barn is an area unit used almost exclusively in nuclear and particle physics, equal to 10⁻²⁸ square meters. Despite its incredibly tiny size, the barn emerged from humorous origins: early nuclear physicists joked that certain atomic nuclei were "as big as a barn" compared to the particles trying to hit them. The barn quantifies interaction cross-sections—essentially probabilities of particles colliding or interacting with nuclei. Because fundamental forces operate at extremely small scales, typical cross-section values lie in the microbarn, nanobarn, or picobarn range. The barn is essential for describing reaction rates in particle accelerators, nuclear reactors, and astrophysical processes such as stellar fusion.
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.