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CHEMISTRY · CALCULATE · UNDERSTAND

Molar Mass Calculator

Parse a chemical formula, audit atom counts, sum atomic weights, and convert between formula mass, sample mass, and amount.

Introductory chemistry

Enter your values

Use a decimal point or scientific notation (1e-3). Choose units before calculating.

Supports element symbols, (), [], hydration dots, Unicode subscripts/digits, and terminal charges such as SO4^2−.
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Calculations run on your device. No account, name or email is required.

Your result

Enter your values and press Calculate to see your answer and all five solution steps.

M = Σ(nᵢAᵢ); m = nM; n = m/M

Common Mistakes

  • Do not read CO as cobalt: CO is C + O, whereas Co is cobalt.
  • Apply a subscript outside parentheses to every atom in that group: Al2(SO4)3 contains O12, not O4.
  • A hydrate coefficient multiplies its whole part: CuSO4·5H2O adds H10O5.
  • Use formula mass for ionic solids; their formula does not normally describe a discrete molecule.

Assumptions and limitations

  • Atomic weights are CIAAW-based educational values. Natural isotopic variation and measurement uncertainty can make laboratory values differ in the last digits.
  • For elements without a CIAAW standard atomic weight, the calculator states the isotope mass number it uses; isotope-specific exact masses require a separate tool.
  • The parser is for a single formula only, not equations, isotope labels, structural formulas, mixtures, or coordination nomenclature.

M = Σ(nᵢAᵢ); m = nM; n = m/M

Learn More

Connect the calculation to your chemistry course and try a related tool.

Mole CalculatorStoichiometry CalculatorPercent Composition CalculatorCourse guides and free testsUniversity chemistry tutoring
Scientific references

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