Proton is about 1.7 fm, or ≈ 62,400 times smaller than a hydrogen atom. Found in the heart of every atom. Each proton is made of three quarks, glued together by particles called gluons.

Proton: how big is it?

Proton is about 1.7 fm. In everyday terms, that is ≈ 62,400 times smaller than a hydrogen atom.

Size: 1.7 fm
In metres: 1.70 × 10⁻¹⁵ m
Everyday comparison: ≈ 62,400 times smaller than a hydrogen atom
Chapter: Inside the Nucleus

Did you know?

Found in the heart of every atom. Each proton is made of three quarks, glued together by particles called gluons.

How it compares

About 1,700× bigger than Quark (upper limit) (1.0 × 10⁻¹⁸ m).
About 2× smaller than Helium nucleus (3.4 fm).

See it on the zoom

Other things of a similar size

Quark (upper limit) 1.0 × 10⁻¹⁸ m
Helium nucleus 3.4 fm
Uranium nucleus 15 fm
Hydrogen atom 106 pm
Water molecule 275 pm
Gold atom 288 pm

Sizes are rounded, typical values drawn from standard reference sources, including NIST/CODATA physical constants and NASA's planetary fact sheets. Real objects vary; see About for how sizes are chosen.