Free Chemistry Calculator

Molar Mass Calculator

Enter a chemical formula to calculate its molar mass from standard atomic weights. The result includes parsed atom counts and each element’s contribution to one mole of the formula unit.

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Calculate molar mass from a formula

Use element symbols with correct capitalization. Parentheses, square brackets, and hydrate dots are supported.

Element symbols are case-sensitive; use a middle dot or period for hydrates.
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What is a molar mass calculator?

A molar mass calculator adds the standard atomic-weight contribution of every atom in a chemical formula. It is a formula parser, not merely a lookup table. Use the Grams to Moles Calculator when a measured sample mass must be converted after the formula mass is known.

How does the molar mass calculator work?

The parser identifies each element symbol, applies its following subscript, expands parenthesized or bracketed groups, and applies hydrate multipliers. It then multiplies every atom count by the corresponding atomic weight and adds the contributions. The same parsed formula powers the Percent Composition Calculator.

What formula does molar mass use?

Molar mass equals the sum of each element’s atom count multiplied by that element’s standard atomic weight: M = Σ(nᵢ × Aᵢ). Values are displayed in grams per mole for the entered formula unit.

How do you enter a chemical formula correctly?

Capitalize the first letter of every element symbol and use lowercase only where the symbol requires it, as in NaCl. Put subscripts after elements or closed groups. Balance a reaction separately with the Chemical Equation Balancer; coefficients before formulas do not belong in a single molar-mass entry.

What do the molar mass results mean?

The main result is the mass of one mole of formula units. The breakdown shows atom counts and each element’s mass share before rounding. For a simplest-formula problem, continue with the Empirical Formula Calculator.

Why can published molar masses differ slightly?

Standard atomic weights may be expressed as intervals because natural isotopic composition can vary. This calculator uses conventional abridged values suitable for general calculations; isotope-specific exact masses require a dedicated reference. Use the Scientific Calculator when retaining additional digits in downstream work.

Who should use this molar mass calculator?

It is intended for classroom, laboratory-preparation, and general chemistry calculations involving neutral formulas and formula units. Verify isotopically labeled compounds, polymers with variable repeat counts, and regulated laboratory work against the applicable method or reference material.

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Frequently asked questions about Molar Mass

Molar mass is the mass of one mole of specified entities, commonly expressed in grams per mole.
They are closely related but not identical terms: relative molecular mass is dimensionless, while molar mass has units such as g/mol.
Yes. It expands nested parentheses and square brackets before adding atomic-weight contributions.
Yes. Use a middle dot or period between the main compound and the hydrate multiplier.
Yes. CO represents carbon and oxygen, while Co is the symbol for cobalt.
The calculator uses conventional abridged standard atomic weights aligned with commonly used NIST periodic-table values.
Enter the neutral chemical formula or formula unit without a trailing charge; electron mass is outside this calculator’s scope.
An isotope-specific exact mass uses selected nuclides, while this calculator uses average or conventional atomic weights for natural elemental composition.

Sources and methodology

The calculation method and explanatory context can be checked against these authoritative primary references.

Scope: This free tool supports learning and planning. Confirm important laboratory, academic, medical, environmental, or industrial work with current protocols and qualified review.
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