⚗️ Molar Mass Calculator

What This Calculator Does

This calculator adds up the molar mass of a compound — the mass of one mole (6.022 × 10²³ molecules) of that substance, expressed in grams per mole (g/mol). Just choose each element in the compound and how many atoms of it are present.

The Formula

Molar mass is a simple sum: for every element in the formula, multiply its standard atomic weight (from the periodic table) by the number of atoms of that element, then add all the contributions together. For example, water (H₂O) is 2 hydrogen atoms (1.008 g/mol each) plus 1 oxygen atom (15.999 g/mol), for a total of about 18.02 g/mol.

A Few Notes

• Atomic weights used here are standard values rounded to match common reference tables; results may differ slightly from more precise sources in the last decimal place.
• Leave the optional Element 3 and Element 4 slots set to “None” for compounds with only two elements.
• This tool is for general educational and reference use.