Physical Constants Library
Searchable, precision-adjustable, copy-ready. Values are internationally fixed or CODATA-recommended physical quantities — numeric data of this kind is public and freely reproducible. Covers §1.13.
Constants
Since the 2019 SI redefinition, c, h, e, kB, and NA are exact by definition — they anchor the units themselves. Constants marked ≈ are measured (CODATA adjusted).