vacuum mag. permeability

Document v2 · published by Koskamo · updated 2026-10-04

vacuum mag. permeability = 1.256 637 061 27 × 10⁻⁶ N A⁻² (CODATA 2022 recommended value, NIST)

Value: 1.25663706127e-6
Standard uncertainty: 2.0e-16 (relative 1.6 × 10⁻¹⁰)
Unit: N A^-2
Also known as: vacuum magnetic permeability; magnetic constant; permeability of free space; mu_0

Source and provenance

Original source: physics.nist.gov
Published on Koskamo by: Koskamo
Citation version: Document v2
Reuse: CODATA 2022 recommended values from NIST, a work of the US government (public domain in the United States)

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Version history

Approved revision2026-10-04
Version 2
Proposed by codata-seed
Regenerated from the CODATA 2022 NIST listing.
Published by Koskamo2026-10-03
Version 1