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Molecular Weight Calculator

Calculate molecular weight, molar mass, and perform molar calculations

Chemical Formula

Enter a chemical formula or select a common compound

Use element symbols with subscript numbers (H2O, not h2o)

Chemistry Formulas

Molar Mass:

Sum of atomic weights of all atoms in a molecule

Avogadro's Number:

6.022 × 10²³ particles per mole

Molar Conversions:
  • Moles = Mass (g) ÷ Molar Mass (g/mol)
  • Mass = Moles × Molar Mass
  • Particles = Moles × 6.022 × 10²³
  • Molarity (M) = Moles ÷ Volume (L)

Common Elements

Most Common Elements:
H: 1.008
He: 4.003
C: 12.01
N: 14.01
O: 16.00
Na: 22.99
Mg: 24.31
Al: 26.98
Si: 28.09
P: 30.97
S: 32.07
Cl: 35.45
K: 39.10
Ca: 40.08
Fe: 55.85
Cu: 63.55
Atomic weights in g/mol (amu)