The helix diameter of a DNA double helix is about 18.9 times the characteristic size of a hydrogen atom. Selected basis: a representative value for Hydrogen atom; a representative value for DNA double helix; approximate values.
The ring marks the true-scale position of a hydrogen atom; it does not show its width. Only the inset is enlarged (×12.4).
Both rulers start at the same zero and share one linear scale. Artwork keeps its original proportions.
105.8 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 constants2 nm - Helix diameter; representative.
DNA is the molecule that stores hereditary information in living organisms. Two nucleotide strands wind around one another to form its double helix.
A 2 nm diameter scale for B-form double-stranded DNA. The pictured strand length is illustrative, not the selected measurement.
University of Utah — Cell size and scale
There’s always another scale
MicroscopicHydrogen atom105.8 pmA hydrogen atom is the simplest neutral atom, with one proton in its nucleus and one electron around it.
MicroscopicDNA double helix2 nmDNA is the molecule that stores hereditary information in living organisms.
Fundamental physicsProton1.682 fmA proton is a positively charged particle found in the nucleus of atoms, made up of quarks.
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?