Planck constant in eV/Hz
UniversalExact
= 4.135 667 696… × 10−15 eV Hz−1
- Value
- 4.135 667 696… × 10−15 eV Hz−1
- Standard uncertainty
- exact
- Relative uncertainty
- exact
- Status
- Exact since the 2019 SI redefinition
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
NIST prints this exact value cut to 10 digits. ConstantID recomputes it from the defining constants: 4.135 667 696 923 858 646 162 230 824 29 × 10−15…
Use in a calculation
# Planck constant in eV/Hz, CODATA 2022 (NIST)
planck_constant_in_ev_hz = 4.1356676969238586461622308242949947e-15 # eV Hz^-1, exact
# SciPy: scipy.constants.physical_constants['Planck constant in eV/Hz']What it is
The Planck constant expressed in electronvolts per hertz.
It is built only from constants that have exact values since 20 May 2019, so it is exact too; CODATA 2018 was the first adjustment to list it that way.
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm2 g s−1) | 6.626 070 15 × 10−27 | exact |
Converted with ConstantID's unit table; digits are rounded to the precision of the value, and a long exact value is rounded only for display.
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). Diamonds mark adjustments in which the value was exact.
Relative uncertainty
| CODATA | Value (uncertainty) | Relative uncertainty | Change from previous |
|---|---|---|---|
| 2022 | 4.135 667 696… × 10−15 | exact | exact |
| 2018 | 4.135 667 696… × 10−15 | exact | +1.4 σ of 2014 |
| 2014 | 4.135 667 662(25) × 10−15 | 6.0 × 10−9 | +1.6 σ of 2010 |
| 2010 | 4.135 667 516(91) × 10−15 | 2.2 × 10−8 | +1.9 σ of 2006 |
| 2006 | 4.135 667 33(10) × 10−15 | 2.4 × 10−8 | −0.3 σ of 2002 |
| 2002 | 4.135 667 43(35) × 10−15 | 8.5 × 10−8 | +1.0 σ of 1998 |
| 1998 | 4.135 667 27(16) × 10−15 | 3.9 × 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).