Physical Constants Reference
Look up the modern CODATA values of 40+ fundamental physical constants — speed of light, Planck, Avogadro, Boltzmann and more — with symbols, units and one-click copy.
| Constant | Symbol | Value |
|---|
Values follow the CODATA recommended set. Constants defining the SI (exact) carry no uncertainty; others are rounded.
About Physical Constants Reference
This reference lists more than forty fundamental physical constants with their modern CODATA values — the speed of light, the Planck constant, the elementary charge, the Avogadro and Boltzmann constants, particle masses, and practical values like standard gravity and the astronomical unit. Each row shows the accepted name, symbol, value in scientific notation and SI unit.
Constants are organized into six categories — universal, electromagnetic, atomic and nuclear, physico-chemical, adopted values and astronomical — with filter chips to browse one group at a time. Constants that are exact by definition in the SI, such as c and h, carry an EXACT badge so you know there is no measurement uncertainty to worry about.
A search box matches names and symbols, and every row offers two copy buttons: one for the symbol and one for the value in plain-text scientific notation, ready to paste into homework, code or a paper.
How to use Physical Constants Reference
- Scan the table of 40+ constants, each with its name, symbol, value in scientific notation and SI unit.
- Filter by category — universal, electromagnetic, atomic, physico-chemical, adopted or astronomical — using the chips above the table.
- Type a name or symbol in the search box (for example Boltzmann or ħ) to jump straight to a constant.
- Look for the EXACT badge to see which values are fixed by definition in the SI rather than measured.
- Click the copy buttons on any row to copy the symbol or the value to your clipboard.