Molar mass constant = 1.000 000 001 05 × 10−3 kg·mol⁻¹

Value
1.000 000 001 05 × 10−3
Unit
kg·mol⁻¹
Uncertainty
0.000 000 000 31 × 10⁻³
Copy-ready
1.00000000105e-3

The molar mass constant M_u, relating relative atomic mass to molar mass.

No longer exactly 1 g/mol since the 2019 SI; the difference is within its quoted uncertainty.

NIST, Fundamental Physical Constants — Complete Listing (2022 CODATA adjustment), retrieved 2026-07-26.

Electrical, thermal and X-ray constants

Angstrom starConductance quantumCopper x unitElectron charge to mass quotientFermi coupling constantFirst radiation constantHartree energyJosephson constantLattice parameter of siliconLattice spacing of ideal Si (220)Loschmidt constant (273.15 K, 101.325 kPa)Magnetic flux quantumMolar mass constantMolar mass of carbon-12Molar Planck constantMolar volume of siliconMolybdenum x unitNeutron-proton mass differenceProton charge to mass quotientQuantum of circulationSackur-Tetrode constant (1 K, 101.325 kPa)Second radiation constantVon Klitzing constantWeak mixing angleWien frequency displacement law constantW to Z mass ratio

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All physical constants

Constants and formula sheetElectrical, thermal and X-ray constantsAll calculators