Empirical Formula Calculator

Enter a percent composition or the masses of each element and this returns the empirical formula, with the moles, the ratio against the smallest, and the multiplier that turned those ratios into whole numbers all shown as separate steps. Adding a molar mass gives the molecular formula as well, and a second form goes straight from an empirical formula and a molar mass to the molecular one. It reports the worst rounding it had to do and flags a multiplier large enough to suggest the figures are not from one pure compound, because forcing a ratio into integers is exactly where this calculation goes wrong. Atomic weights are the IUPAC standard values and five published molar masses are re-derived on every run as a check on the table.