- Value
- 8.4075 × 10−16
- Unit
- m
- Uncertainty
- 0.0064 × 10⁻¹⁶
- Copy-ready
8.4075e-16
The root-mean-square radius of the proton's charge distribution.
Electron-scattering and muonic-hydrogen measurements once disagreed on it — the 'proton radius puzzle'; CODATA 2022 reflects the resolved value.
NIST, Fundamental Physical Constants — Complete Listing (2022 CODATA adjustment), retrieved 2026-07-26.
Compton wavelengths, radii and cross sections
Link to or cite this value
Link from a web page
Plain HTML for any page that accepts markup.
<a href="https://usephysics.com/reference/proton-rms-charge-radius">Proton rms charge radius — 8.4075 × 10−16 m — UsePhysics</a>
Link from Markdown
For READMEs, wikis and notes.
[Proton rms charge radius — 8.4075 × 10−16 m — UsePhysics](https://usephysics.com/reference/proton-rms-charge-radius)
Cite it in a document
Replace [date] with the day you consulted the page. The line credits NIST/CODATA for the values.
UsePhysics. "Proton rms charge radius — 8.4075 × 10−16 m." UsePhysics.com. https://usephysics.com/reference/proton-rms-charge-radius. Value from the 2022 CODATA adjustment (NIST). Accessed [date].