Molar Mass Calculator

Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). It is numerically equal to the molecular weight or formula weight of the compound, but expressed in different units. One mole of any substance contains exactly 6.022 × 10²³ entities (atoms, molecules, or formula units) — Avogadro's number. Molar mass bridges the gap between the atomic scale (where we count atoms) and the laboratory scale (where we measure grams).

To calculate the molar mass of a compound, you sum the atomic masses of all atoms in its chemical formula. Each element's atomic mass is found on the periodic table and represents the weighted average of its naturally occurring isotopes. For example, water (H₂O) has a molar mass of 2(1.008) + 15.999 = 18.015 g/mol, meaning one mole of water molecules weighs 18.015 grams.

This calculator parses any valid chemical formula — including those with parentheses like Ca(OH)₂ — and provides a complete element-by-element breakdown showing each atom's contribution to the total molar mass. It also displays the percentage composition by mass for each element, which is useful for empirical formula determination and quality control in manufacturing.

The molar mass of a compound is the sum of the atomic masses of all atoms in the formula, each multiplied by the number of times that atom appears.

This calculator provides instant molar mass results from any chemical formula:

1. Enter Chemical Formula: Type the molecular formula using standard notation — capital letters for elements, lowercase for second letters (e.g., NaCl, Ca(OH)₂, C₆H₁₂O₆).
2. Or Select a Common Compound: Click any preset button (H₂O, NaCl, glucose, etc.) to auto-fill the formula.
3. View Results: The calculator displays the total molar mass, element-by-element breakdown with mass contributions and percentages, and quick conversion factors.

The element breakdown table shows each element's atomic mass, the number of atoms, the total mass contribution, and the percentage by mass. The progress bars provide a visual representation of each element's contribution.

The results panel provides several useful pieces of information beyond just the molar mass:

Element Breakdown: Each element is listed with its atomic mass, count, total mass contribution, and percentage. Elements are sorted by contribution, with the heaviest contributors at the top. This breakdown is essential for quality control and for verifying that your formula is correct.

Quick Conversions: The calculator shows that 1 mole equals the molar mass in grams, and 1 gram equals 1/molar mass moles. These conversions are the basis for all stoichiometric calculations. It also notes that 1 mole contains 6.022 × 10²³ molecules and, for gases at STP, occupies 22.4 liters.

Error Detection: If the formula contains an unrecognized element symbol, the calculator reports an error. This helps catch typos like lowercase/uppercase errors (e.g., "co" instead of "Co" for cobalt).

Molar mass calculations are the foundation of stoichiometry, which is the quantitative relationship between reactants and products in chemical reactions. Every laboratory preparation, from making a simple salt solution to synthesizing a complex pharmaceutical, begins with calculating how much of each reagent is needed — and that requires molar mass.

In pharmaceutical manufacturing, molar mass determines drug dosing, formulation ratios, and quality specifications. Active pharmaceutical ingredients are weighed by mass, but their biological activity is determined by the number of molecules, which is calculated from molar mass.

In environmental monitoring, pollutant concentrations are often converted between mass-based and mole-based units using molar mass. In food science, nutritional calculations use molar mass to convert between grams of nutrients and molecules. Even in forensics, molar mass helps identify unknown substances by comparing measured molecular weights to known compounds.