Convert Femtometer (fm) to Mile (US Survey) (mi (US)) 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.
Mile (US Survey) (mi (US))
The US Survey Mile equals 5,280 US Survey Feet (~1,609.347 meters). Slightly longer than the international mile due to the use of the US survey foot, it has been essential for mapping, transportation planning, and geodetic calculations in the United States. Surveyors and engineers relied on the US survey mile to ensure precise alignment of property boundaries, railroad tracks, and infrastructure projects. Over long distances, even small differences between the US survey and international mile can accumulate significantly, necessitating care in measurement. Though the international mile is now standard, the US survey mile remains important for interpreting historical maps, legal descriptions, and older engineering plans.