reduced Planck constant

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

reduced Planck constant = 1.054 571 817… × 10⁻³⁴ J s (CODATA 2022 recommended value, NIST)

Value: 1.054571817e-34 (NIST lists only these digits; the exact value continues)
Uncertainty: none; the value is exact by definition of the SI
Unit: J s
Also known as: h-bar; hbar; Dirac constant

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