Convert Yard (yd) to Femtometer (fm) instantly.
About these units
Yard (yd)
A yard equals 3 feet or 36 inches and serves as a mid-range imperial length unit. Historically, one definition of the yard was the distance from the tip of King Henry I's nose to his thumb when his arm was extended, though later attempts standardized the measure. Today, yards appear in sports (football, golf), textiles (fabric sales), and landscaping. In construction and engineering, the yard is sometimes used for larger distances where a foot would be too small a unit and a mile too large. Because it divides cleanly into both inches and feet, the yard plays a structural role in the imperial measurement system. It bridges the gap between human-scale and large-scale distances.
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.