Water molecule
A water molecule is a group of two hydrogen atoms bonded to one oxygen atom. Its bent arrangement gives water many of its distinctive properties.
How big is it?
280 pm across
Characteristic size · representative
A little perspective
About 2.65 times the characteristic size of Hydrogen atom.
Hydrogen atom: A hydrogen atom is the simplest neutral atom, with one proton in its nucleus and one electron around it.
Measurements, assumptions & sources +
Water molecule
A chosen 0.28 nm molecular-scale model. Effective molecular size depends on the definition.
University of Utah — Cell size and scale
The marked characteristic size is calibrated. Unmeasured illustration details are representative.
Hydrogen atom
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
The marked characteristic size is calibrated. Unmeasured illustration details are representative.
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Why this measurement?
Why we use 280 pm
For comparison, this page uses characteristic size. This is labelled representative; the central value is useful for comparison, while real values or measurement solutions can vary.
A chosen 0.28 nm molecular-scale model. Effective molecular size depends on the definition.
The marked horizontal span follows the named feature; transparent margins and unmeasured details do not alter it. How calibrated comparisons work →
Recorded properties
Water molecule dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 280 pm | Not recorded | representative | |
| 2.992 × 10⁻²⁶ kg | Not recorded | representative |
Around this scale
Go smaller. Go bigger.
These links use compatible length records, ordered around the selected value.
Nearest lower value · MicroscopicHydrogen atom105.8 pmA hydrogen atom is the simplest neutral atom, with one proton in its nucleus and one electron around it.
Nearest higher value · MicroscopicGlucose molecule1 nmA glucose molecule is a simple sugar used by living cells as a source of chemical energy.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.MicroscopicHydrogen atom105.8 pmA hydrogen atom is the simplest neutral atom, with one proton in its nucleus and one electron around it.MicroscopicGlucose molecule1 nmA glucose molecule is a simple sugar used by living cells as a source of chemical energy.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.
MicroscopicDNA double helix2 nmDNA is the molecule that stores hereditary information in living organisms.
MicroscopicIgG antibody molecule14.5 nmAn IgG antibody molecule is a Y-shaped protein produced by the immune system to identify and neutralise foreign substances.