Frequently Asked Questions
Common questions about the Empirical Formula Calculator.
How does the empirical formula calculator work?
Enter percent composition or mass for each element; it converts to moles, finds the smallest whole-number ratio, and shows every step.
Is it free?
Completely free, no sign-up, downloads, or limits.
What's the difference between empirical and molecular formula?
The empirical formula is the simplest whole-number ratio of atoms; the molecular formula is the actual ratio, which can be a multiple of the empirical formula.
Can it find the molecular formula too?
Yes — if you provide the compound's known molar mass, it calculates the multiplier and derives the molecular formula.
What if my percentages don't add up to 100%?
It flags this; you can also use the "solve remaining % as oxygen" option for the classic combustion-analysis problem type.
What if the mole ratio isn't a whole number?
The calculator multiplies all ratios by the smallest integer needed to clear fractions, and shows this step explicitly.
Which elements are supported?
The most common elements by standard atomic weight; unrecognized symbols are flagged.
Does it show the steps?
Yes, the full mole-ratio derivation is shown, not just the final formula.
Is my data stored?
No; everything runs in your browser and isn't stored or sent anywhere.
Does it work on mobile?
Yes, fully responsive on all screen sizes.