Empirical Formula Calculator

How to find an empirical formula

1. Type each element with its percent by mass or its mass in grams, one per line, such as C 40.0.
2. Add the molar mass, if you know it, to get the molecular formula too.
3. The empirical formula appears with its formula mass and the mole ratio of the elements.

Frequently asked questions

How does it work?

Each mass is divided by the element's atomic weight to get moles, the moles are divided by the smallest, and the ratios are multiplied by the smallest whole number that makes them all within 0.1 of a whole number.

How is the molecular formula found?

The molar mass is divided by the empirical formula mass and rounded to a whole number, and every subscript is multiplied by it. C 40.0, H 6.7, O 53.3 with 180.16 g/mol gives CH2O and C6H12O6.