Molar Mass Calculator
Every Chemical Formula Has a Weight Hidden in Its Subscripts
Molar mass is the bridge between the atomic world and the lab bench: it converts a formula written on paper into a number of grams you can actually weigh out. Get it wrong by even a rounding error on a multi-gram synthesis and a titration or a reaction yield calculation downstream will be off. This calculator parses a formula — including nested parentheses like Ca(OH)2 — and sums the contribution of every atom using IUPAC standard atomic weights.
The Formula
For a compound such as glucose (C6H12O6), that means summing 6 carbons, 12 hydrogens, and 6 oxygens, each multiplied by its own standard atomic weight, then adding the subtotals together.
Where This Calculation Matters
- Weighing out a solution — converting a target molarity into grams to measure on a balance requires the molar mass of the solute first.
- Stoichiometry — every mole-to-gram or gram-to-mole conversion in a reaction depends on this number for each species involved.
- Verifying a compound's identity — comparing a measured molar mass against the calculated value for a proposed formula is a standard check in synthesis work.
- Dosing and formulation — pharmaceutical and nutritional calculations that start from a molar quantity need to be converted to mass for practical measurement.
Molar Masses of Common Compounds
| Compound | Formula | Molar Mass (g/mol) |
|---|---|---|
| Water | H2O | 18.015 |
| Sodium chloride | NaCl | 58.440 |
| Carbon dioxide | CO2 | 44.009 |
| Glucose | C6H12O6 | 180.156 |
| Calcium carbonate | CaCO3 | 100.086 |
| Sulfuric acid | H2SO4 | 98.072 |
| Sodium hydroxide | NaOH | 39.997 |
| Sucrose | C12H22O11 | 342.297 |
Values are rounded to three decimal places using the IUPAC conventional atomic weights this calculator applies internally.
How to Use This Calculator
- Type the chemical formula into the Chemical Formula field, using standard capitalization (e.g.
Ca(OH)2, notca(oh)2). - Include subscripts as plain numbers immediately after each element symbol, and use parentheses for grouped fragments that repeat.
- Select Calculate to get the total molar mass along with a line-by-line breakdown of each element's contribution.
Related Calculations
Once you have a molar mass, use the Moles Calculator to convert a sample's mass into moles, or the Molarity Calculator to work out solution concentration from that mass.