Proton magnetic moment to nuclear magneton ratio

$μₚ/μ_N$ = 2.792 847 344 63(82)

Value: 2.792 847 344 63
Standard uncertainty: 8.2 × 10⁻¹⁰
Relative uncertainty: 2.9 × 10⁻¹⁰ (294 parts per trillion)
Status: Measured
Symbol: $μₚ/μ_N$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# proton magnetic moment to nuclear magneton ratio, CODATA 2022 (NIST)
proton_magnetic_moment_to_nuclear_magnet = 2.79284734463  # standard uncertainty 8.2e-10

# SciPy: scipy.constants.physical_constants['proton mag. mom. to nuclear magneton ratio']

What it is

The magnetic moment of the proton, the nucleus of the hydrogen atom, expressed in nuclear magnetons.

How the value changed, 1998–2022

Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).

Relative uncertainty

CODATA	Value (uncertainty)	Relative uncertainty	Change from previous
2022	2.792 847 344 63(82)	2.9 × 10⁻¹⁰	+0.0 σ of 2018
2018	2.792 847 344 63(82)	2.9 × 10⁻¹⁰	−0.7 σ of 2014
2014	2.792 847 3508(85)	3.0 × 10⁻⁹	−0.2 σ of 2010
2010	2.792 847 356(23)	8.2 × 10⁻⁹	+0.0 σ of 2006
2006	2.792 847 356(23)	8.2 × 10⁻⁹	+0.2 σ of 2002
2002	2.792 847 351(28)	1.0 × 10⁻⁸	+0.5 σ of 1998
1998	2.792 847 337(29)	1.0 × 10⁻⁸

“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).