DNA double helix
DNA is the molecule that stores hereditary information in living organisms. Two nucleotide strands wind around one another to form its double helix.
How big is it?
2 nm across
Helix diameter · representative
A little perspective
About twice the characteristic size of Glucose molecule.
Glucose molecule: A glucose molecule is a simple sugar used by living cells as a source of chemical energy.
Measurements, assumptions & sources +
DNA 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
The marked helix diameter is calibrated. Unmeasured illustration details are representative.
Glucose molecule
A one-nanometre scale model of a glucose molecule; orientation affects its span.
University of Utah — Cell size and scale
The marked characteristic size is calibrated. Unmeasured illustration details are representative.
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Why this measurement?
Why we use 2 nm
For comparison, this page uses helix diameter. This is labelled representative; the central value is useful for comparison, while real values or measurement solutions can vary.
A 2 nm diameter scale for B-form double-stranded DNA. The pictured strand length is illustrative, not the selected measurement.
The marked horizontal span follows the named feature; transparent margins and unmeasured details do not alter it. How calibrated comparisons work →
Recorded properties
DNA double helix dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 2 nm | Not recorded | representative |
Around this scale
Go smaller. Go bigger.
These links use compatible length records, ordered around the selected value.
Nearest lower value · MicroscopicGlucose molecule1 nmA glucose molecule is a simple sugar used by living cells as a source of chemical energy.
Nearest higher value · MicroscopicIgG antibody molecule14.5 nmAn IgG antibody molecule is a Y-shaped protein produced by the immune system to identify and neutralise foreign substances.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- University of Utah — Cell size and scaleApproximate biological size regimes. Atlas specimens and geometric assumptions are individually labelled.
More ways to see it
Curated comparisons
There’s always another scale
Follow your curiosity.
Fundamental physicsProton1.682 fmA proton is a positively charged particle found in the nucleus of atoms, made up of quarks.
Microscopic10 µm cell10 µmA cell is the basic structural unit of living organisms.
People70 µm hair70 µmA hair is a slender strand of protein that grows from the skin of humans and other mammals.MicroscopicGlucose molecule1 nmA glucose molecule is a simple sugar used by living cells as a source of chemical energy.
MicroscopicWater molecule280 pmA water molecule is a group of two hydrogen atoms bonded to one oxygen atom.MicroscopicIgG antibody molecule14.5 nmAn IgG antibody molecule is a Y-shaped protein produced by the immune system to identify and neutralise foreign substances.
MicroscopicRibosome25 nmA ribosome is a molecular machine that builds proteins by reading instructions carried by messenger RNA.
Fundamental physicsBohr radius52.92 pmThe Bohr radius is a fundamental physical constant representing the most probable distance between the nucleus and the electron in a hydrogen atom according to early quantum theory.