- Symbol
- ℏ
- Value
- 1.054 571 817... × 10−34
- Unit
- J·s
- Uncertainty
- exact (by definition)
- Copy-ready
1.054571817e-34
h/2π. Exact by definition, but the decimal does not terminate — the trailing dots are NIST's, not a rounding.
NIST, Fundamental Physical Constants — Complete Listing (2022 CODATA adjustment), retrieved 2026-07-26.
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UsePhysics. "Reduced Planck constant — 1.054 571 817... × 10−34 J·s." UsePhysics.com. https://usephysics.com/reference/reduced-planck-constant. Value from the 2022 CODATA adjustment (NIST). Accessed [date].