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AMU to Grams per Mole Converter

↔ Convert g/mol to amu instead

Common Conversions

amu g/mol
1.008 1.008
4.003 4.003
12 12
14.007 14.007
15.999 15.999
23 23
35.45 35.45
55.845 55.845
63.546 63.546
107.87 107.87
196.97 196.97

Why this conversion matters in chemistry

Look at a mass spectrum: a peptide peak at 1547.74 u and the same peptide's database entry at 1547.74 g/mol carry exactly the same number. That isn't a coincidence — Avogadro's number was chosen specifically so that one mole of carbon-12 atoms (each weighing 12 u) would weigh exactly 12 grams. Every other equality between per-atom mass in amu and per-mole mass in g/mol follows from that single anchor. In practice you treat this conversion as an identity — useful mostly as a sanity check that no spurious factor of Nₐ has crept into a calculation moving between single-molecule and molar scales.

Formula

g/mol = amu × 1 (numerically identical)

Worked Examples

1.008 amu = 1.008 g/mol

Hydrogen — the lightest case, where atomic mass and molar mass write as the same number.

12 amu = 12 g/mol

Carbon-12 by definition — the calibration anchor that pins both the u and g/mol scales.

35.45 amu = 35.45 g/mol

Chlorine standard atomic weight — naturally occurring isotope mix, not a single nuclide.

196.97 amu = 196.97 g/mol

Gold — a heavy single-isotope element that closes the textbook range cleanly.

Frequently Asked Questions

Are amu and g/mol the same number?
Yes — exactly. A particle of mass 12 amu corresponds to a molar mass of 12 g/mol for that species. The equivalence is built into the mole concept and rests on Avogadro's number.
Why is this conversion so simple?
The mole was defined so that the per-atom mass in amu and the per-mole mass in g/mol carry the same number. Avogadro's number is the bridge: mass_per_atom (amu) × Nₐ atoms = molar_mass (g/mol).
When does the conversion show up?
Mass-spectrometry results report in u or Da; downstream stoichiometry needs molar mass in g/mol. The conversion is the identity at that boundary — useful as a sanity check that no accidental factor crept into a peptide-ID workflow or a fragmentation calculation.
What about isotope-specific masses?
Individual isotopes — ¹³C at 13.003 u, ²H at 2.014 u — differ from the standard atomic weights (averaged over natural abundance). Molar-mass calculations use the standard weight; isotope-labelling work uses the specific isotope mass.