Convert Square Perch (perch²) to Barn (b (area)) instantly.
About these units
Square Perch (perch²)
A square perch is equivalent to a square rod, as "perch" was another historical name for a rod, used in various medieval and regional English measurement systems. Perches commonly appeared in church records, tithing assessments, and agricultural inventories. Because the perch was both a length and an area unit, it played dual roles in land taxation and construction. These overlapping terminologies—rod, pole, perch—reflect the organic evolution of measurement in medieval Europe, long before unified systems took hold.
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.