About the Empirical Formula Calculator

Percent composition converts to an atom ratio in three steps: divide each percent by the element's atomic mass (giving mole amounts), divide every result by the smallest, and round to whole numbers. For 40.00% C, 6.71% H, 53.29% O: 3.33 : 6.66 : 3.33 moles → 1 : 2 : 1, so CH₂O.

From Empirical to Molecular

The empirical formula is a ratio, not a molecule — many compounds share it. The molecular formula needs the actual molar mass: n = molar mass ÷ empirical mass. With 30.03 g/mol and empirical mass 30.03, n = 1 and the molecular formula equals the empirical formula; for glucose (180.16 g/mol), n = 6 gives C₆H₁₂O₆.