Convert Femtometer (fm) to Barleycorn (barleycorn) instantly.
About these units
Femtometer (fm)
A femtometer, equal to 10⁻¹⁵ meters, is the scale at which the structure of atomic nuclei becomes measurable. Also known historically as a "fermi," this unit is used extensively in nuclear physics to describe the radii of protons, neutrons, and nuclei, which typically span 1–10 femtometers. At this scale, the strong nuclear force dominates interactions, and classical intuition breaks down almost entirely—quantum mechanics provides the only meaningful framework. The femtometer also plays a role in high-energy particle experiments, where the wavelengths of probing particles (like high-velocity electrons) may be expressed in femtometer increments. These small wavelengths allow researchers to resolve sub-nuclear structures. While invisible to any optical instrument, distances in the femtometer range can be inferred through scattering experiments, such as those performed in particle accelerators.
Barleycorn (barleycorn)
The barleycorn is an English unit, approximately 1/3 inch (8.47 mm), originally based on the length of a grain of barley. It served as a small-scale measure in tailoring, shoe sizing, and other crafts. In particular, the English shoe size system was historically based on barleycorns, with increments in size corresponding to single barleycorn units. This unit exemplifies the anthropometric and agronomic origins of measurement. Even today, the barleycorn's influence persists in the traditional shoe sizing system in the UK and the US, providing continuity with historical practices.