Molar Mass Calculator

How to use this calculator

1. Select up to three elements and enter their atom counts.
2. Enter moles of the compound if you want sample mass as well.
3. We sum atomic weights for molar mass and multiply by moles to get grams.

Inputs explained

Element symbols

Pick elements for your formula (up to three in this version).

Atom counts

Number of atoms of each selected element in the molecule.

Moles of compound

Optional. Multiply molar mass by this to get sample mass.

When to use it

• Checking homework problems that require molar mass and grams from moles.
• Building quick reagent lists for small lab preps.
• Estimating shipping weight when ordering compounds in specific moles.

Tips & cautions

• Combine like elements if your molecule has more than three unique atoms (e.g., group multiple carbons together).
• Atomic weights are averages—use isotope-specific masses if your application requires that precision.
• Keep atom counts as whole numbers; fractional counts imply mixtures rather than molecules.
• Supports up to three elements; complex molecules require manual grouping.
• Uses average atomic weights, not isotope-specific masses.
• Does not balance equations or handle charges—this is purely a molar mass sum.

Worked examples

Deep dive

FAQs

Need more than three elements?

Combine like elements manually or run the calculator twice—future updates will support more slots.

Are atomic weights exact?

We use standard average atomic weights. Isotopic samples vary slightly.

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