Electron magnetic moment to nuclear magneton ratio

$μₑ/μ_N$ = −1838.281 971 877(32)

Value: −1838.281 971 877
Standard uncertainty: 3.2 × 10⁻⁸
Relative uncertainty: 1.7 × 10⁻¹¹ (17 parts per trillion)
Status: Measured
Symbol: $μₑ/μ_N$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# electron magnetic moment to nuclear magneton ratio, CODATA 2022 (NIST)
electron_magnetic_moment_to_nuclear_magn = -1.838281971877e3  # standard uncertainty 3.2e-8

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

What it is

The magnetic moment of the electron, the lightest charged particle and the carrier of electric current in metals, 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	−1838.281 971 877(32)	1.7 × 10⁻¹¹	+0.0 σ of 2018
2018	−1838.281 971 88(11)	6.0 × 10⁻¹¹	+2.7 σ of 2014
2014	−1838.281 972 34(17)	9.2 × 10⁻¹¹	−1.9 σ of 2010
2010	−1838.281 970 90(75)	4.1 × 10⁻¹⁰	+0.0 σ of 2006
2006	−1838.281 970 92(80)	4.4 × 10⁻¹⁰	+0.2 σ of 2002
2002	−1838.281 971 07(85)	4.6 × 10⁻¹⁰	−1.3 σ of 1998
1998	−1838.281 9660(39)	2.1 × 10⁻⁹

“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).