Molar Mass Calculator 2026 — GlobalCalc

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Inputs

Chemical formula

Use exact symbol case (Na, Cl, Mg); brackets and ·xH2O hydrates are understood.

Results update as you type

Results

Molar mass

180.156 g/mol

Atoms per formula unit—

By element—

Mass percent—

Reviewed September 2026. Chemistry is the same in every country: SI and laboratory units throughout.

All calculations run 100% in your browser. The calculator code does not submit your figures to GlobalCalc to obtain a result.

About molar mass

Method

How the molar mass calculator works

Molar mass is the sum of the atomic masses of every atom in the formula, in grams per mole. The calculator parses element symbols (case matters: Co is cobalt, CO is carbon monoxide), subscripts, brackets with multipliers and hydrate dots, multiplies each element's count by its IUPAC atomic mass and adds them up.

The breakdown shows each element's contribution and mass percentage — the numbers behind empirical-formula and percent-composition questions.

Formula: M = Σ (atoms of each element × atomic mass)

Data

Worked examples

Inputs	Molar mass	Note
Glucose, C6H12O6	180.156 g/mol	180.156 g/mol
Water, H2O	18.015 g/mol	18.015 g/mol
Calcium hydroxide, Ca(OH)2	57.085 g/mol	brackets with a multiplier
Copper sulfate pentahydrate, CuSO4·5H2O	249.677 g/mol	a hydrate

FAQ

Frequently asked questions

What is the difference between molar mass and molecular weight?

Numerically the same for a molecule; molar mass is expressed in g/mol, molecular (or formula) weight in atomic mass units. Ionic compounds have a formula mass rather than a molecular one.

Why does capitalization matter?

Every symbol starts with a capital: CO is carbon monoxide (one carbon, one oxygen); Co is cobalt. The calculator reads symbols exactly as the periodic table writes them.

How are hydrates handled?

The dot (· or .) means "plus": CuSO4·5H2O adds five water molecules to the formula unit — 159.61 + 5 × 18.015 = 249.68 g/mol.

Which atomic masses are used?

IUPAC conventional values (e.g. C 12.011, O 15.999, Cl 35.45). Exam boards sometimes round differently (C 12.0, O 16.0), which shifts results in the second decimal.

Sources

Where these figures come from

IUPAC — Standard atomic weights (2021 conventional values) — the molar-mass table
NIST — CODATA 2018 fundamental physical constants — Avogadro constant, gas constant, speed of light
NIST Chemistry WebBook — thermochemical data
National Institute of Standards and Technology — the US measurement and reference-data authority

Last checked: September 2026. Atomic masses are the IUPAC conventional values; constants are CODATA 2018; equations are the standard textbook forms.