Physics Constants

The copy button preserves the listed decimal text without extra rounding. Uncertainty u is in the row’s unit; 0 denotes an exact definition or conversion, not perfect knowledge of a physical object. Irrational exact relations have rounded decimal representations. Solar nominal conversions do not assert unchanging solar properties. The solar mass is estimated from nominal GM divided by measured G. H₀ is the model-dependent Planck 2018 ΛCDM estimate, not a universal fixed definition. A light-year uses a Julian year of 365.25 days.

Search and category combine immediately; an empty match does not erase either input. Search, category and sorting survive reload; no copied values or result history are saved. Click a value to copy its exact machine-readable decimal text, without its unit. The value shows a brief check mark, or an exclamation mark if clipboard access fails; the tooltip and screen reader explain the outcome. Numeric sorting orders the displayed numbers only; values with different dimensions are not physically comparable.