The characteristic size of a hydrogen atom is about 62,900 times the diameter of a proton. Selected basis: a representative value for Hydrogen atom; approximate values.
The ring marks the true-scale position of a proton; it does not show its width. Only the inset is enlarged (×23,900).
Both rulers start at the same zero and share one linear scale. Artwork keeps its original proportions.
1.682 fm - Diameter; measured constant.
A proton is a positively charged particle found in the nucleus of atoms, made up of quarks.
Twice the approximately 0.8409 fm charge radius. The charge distribution has no hard boundary; the illustration is schematic.
NIST — 2022 CODATA fundamental constants105.8 pm - Characteristic size; representative.
A hydrogen atom is the simplest neutral atom, with one proton in its nucleus and one electron around it.
A diameter of twice the Bohr radius, used as a characteristic scale. An electron cloud has no hard outer surface.
NIST — 2022 CODATA fundamental constants
There’s always another scale
Fundamental physicsProton1.682 fmA proton is a positively charged particle found in the nucleus of atoms, made up of quarks.
MicroscopicHydrogen atom105.8 pmA hydrogen atom is the simplest neutral atom, with one proton in its nucleus and one electron around it.
Fundamental physicsPlanck length1.616 × 10⁻³⁵ mThe Planck length is a scale formed from fundamental physical constants.
MicroscopicDNA double helix2 nmDNA is the molecule that stores hereditary information in living organisms.
MicroscopicCell10 µmA cell is the basic structural unit of living organisms.
PeopleHair70 µmA hair is a slender strand of protein that grows from the skin of humans and other mammals.Side by side
Illustrative artwork · not to scale
Illustrative artwork · not to scale
Illustrative artwork · not to scale
Illustrative artwork · not to scaleGot a good eye for scale?