Atomic nucleus
An atomic nucleus is the compact central part of an atom, made from protons and neutrons. Nearly all of an atom’s mass is concentrated there.
How big is it?
10 fm across
Characteristic size · representative
A little perspective
About 5.95 times the diameter of Proton.
Proton: A proton is a positively charged particle found in the nucleus of atoms, made up of quarks.
Measurements, assumptions & sources +
Atomic nucleus
A 10 fm diameter scale model of a heavy nucleus. Nuclear size depends on the number of nucleons.
University of Utah — Cell size and scale
The marked characteristic size is calibrated. Unmeasured illustration details are representative.
Proton
Twice the approximately 0.8409 fm charge radius. The charge distribution has no hard boundary; the illustration is schematic.
NIST — 2022 CODATA fundamental constants
The marked diameter is calibrated. Unmeasured illustration details are representative.
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Why this measurement?
Why we use 10 fm
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 10 fm diameter scale model of a heavy nucleus. Nuclear size depends on the number of nucleons.
The marked horizontal span follows the named feature; transparent margins and unmeasured details do not alter it. How calibrated comparisons work →
Recorded properties
Atomic nucleus dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 10 fm | Not recorded | representative |
Around this scale
Go smaller. Go bigger.
These links use compatible length records, ordered around the selected value.
Nearest lower value · Fundamental physicsProton1.682 fmA proton is a positively charged particle found in the nucleus of atoms, made up of quarks.
Nearest higher value · Fundamental physicsElectron2.426 pmAn electron is a fundamental subatomic particle with a negative electric charge, found in atoms and responsible for electricity and chemical bonding.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.Fundamental physicsElectron9.109 × 10⁻³¹ kgAn electron is a fundamental subatomic particle with a negative electric charge, found in atoms and responsible for electricity and chemical bonding.
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.MicroscopicHydrogen atom105.8 pmA hydrogen atom is the simplest neutral atom, with one proton in its nucleus and one electron around it.
MicroscopicWater molecule280 pmA water molecule is a group of two hydrogen atoms bonded to one oxygen atom.
MicroscopicGlucose molecule1 nmA glucose molecule is a simple sugar used by living cells as a source of chemical energy.