The mass of one mole of a substance in grams, numerically equal to the molecular weight in atomic mass units.

Where do I find atomic masses?

On the periodic table. Common ones: H=1.008, C=12.011, N=14.007, O=15.999, Na=22.990, Cl=35.453.

What if my compound has more than 3 elements?

Set unused element counts to zero and calculate remaining elements separately, then add.

Free Molar Mass Calculator

Calculate the molar mass of a compound from the atomic masses and number of each element.

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Atomic Mass of Element A

g/mol

Number of A Atoms

Atomic Mass of Element B

g/mol

Number of B Atoms

Atomic Mass of Element C

g/mol

Number of C Atoms

Molar Mass

180.156 g/mol

Molar Mass vs Atomic Mass of Element A

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How to Calculate Molar Mass

Formula

Mw = sum of (atomic mass × count) for each element

Look up atomic masses on the periodic table and multiply by the subscript in the formula.

Example Calculation

Glucose C6H12O6: C=12.011, H=1.008, O=15.999.

01C: 12.011 × 6 = 72.066
02H: 1.008 × 12 = 12.096
03O: 15.999 × 6 = 95.994
04Mw = 72.066 + 12.096 + 95.994 = 180.156 g/mol

Frequently Asked Questions

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Understanding Molarity

Learn what molarity is, how to calculate it, and why it matters in chemistry. Covers moles, liters, dilution, and step-by-step examples for preparing solutions.

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