Convert Centimeter (cm) to Femtometer (fm) instantly.
About these units
Centimeter (cm)
The centimeter, 1/100 of a meter, strikes a balance between precision and ease of communication, making it indispensable in everyday life. Its size is well-matched to human-scale objects—furniture, body dimensions, school supplies, and clothing—so people in metric countries regularly estimate or visualize lengths in centimeters without tools. Many professions rely heavily on centimeters, including medicine (wound sizes, tumor dimensions), tailoring, building trades, and interior design. In science, centimeters serve as a practical unit for measurements too small for meters but too large for millimeters. Biologists, for example, may measure specimen sizes or growth stages in centimeters. Its intuitive scale and decimal alignment with meters ensure that both laypeople and professionals can convert easily among related 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.