Molar Mass Calculator
Calculate molar mass from any chemical formula, with the contribution of each element listed.
Molar mass, molecular mass, formula mass
They are numerically identical and differ only in units and in what they describe. Molecular mass is one molecule measured in atomic mass units; molar mass is one mole measured in grams. Formula mass is the term used for ionic compounds, which have no discrete molecules. Sulfuric acid is 98.08 in all three senses.
Where lab results and calculated results part company
These relations describe ideal behaviour: ideal gases, complete reactions, fully dissociated strong acids, no side products. Real yields fall short, real gases deviate near condensation, and real solutions show activity effects at higher concentrations. The calculated figure is the target to compare a measurement against, not a prediction of what the flask will contain.
The formula
M = Σ (atomic mass × number of atoms)
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Molar Mass Calculator
- Fill in each field with your own figures — the defaults are only there as an example.
- The result updates as you type, so there is no button to press.
- Check the breakdown under the main result for the supporting numbers.
- Use the copy button to take the result with you, or share the link to reload the same inputs.
Molar Mass Calculator — frequently asked questions
Is this molar mass calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Can I use it on my phone?
Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the molar mass calculator.
- molar mass calculator
- relative molecular mass
- gram formula mass
- formula mass
- molecular weight from formula
- molar mass
About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed September 14, 2026 · Calculation runs client-side · No data collected · Report an error