All things · Inside the Nucleus

Uranium nucleus: how big is it?

Uranium nucleus is about 15 fm. In everyday terms, that is ≈ 7,070 times smaller than a hydrogen atom.

Size

15 fm

In metres

1.50 × 10⁻¹⁴ m

Everyday comparison

≈ 7,070 times smaller than a hydrogen atom

Chapter

Inside the Nucleus

Did you know?

92 protons and about 146 neutrons, packed so tightly that splitting them apart releases enormous energy — the idea behind nuclear power.

How it compares

• About 4.4× bigger than Helium nucleus (3.4 fm).
• About 7,100× smaller than Hydrogen atom (106 pm).

Other things of a similar size

• Quark (upper limit) 1.0 × 10⁻¹⁸ m
• Proton 1.7 fm
• Helium nucleus 3.4 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.