Empirical Formula Calculator

An empirical formula is the simplest whole-number ratio of atoms in a compound. It does not necessarily show the actual number of atoms in one molecule; it shows the reduced ratio. For example, glucose has the molecular formula C6H12O6, but its empirical formula is CH2O because the 6:12:6 ratio reduces to 1:2:1. This calculator follows the standard general chemistry workflow: convert masses or percentages into moles, divide all mole amounts by the smallest value, and then adjust near-fraction ratios into integers.

The tool is especially useful for percent composition problems. When a problem says a substance is 40.00 percent carbon, 6.71 percent hydrogen, and 53.29 percent oxygen, you can treat those percentages as grams in a 100 g sample. After dividing by atomic masses, the mole ratios reveal the empirical formula. If an experimental ratio lands near 1.5, 1.333, 1.25, or another common fraction, the calculator searches small multipliers so the final formula uses whole-number subscripts instead of awkward decimals.

You can also provide a molecular mass to get the molecular formula. The calculator computes the empirical formula mass and compares it with the supplied molar mass. If the molecular mass is close to an integer multiple of the empirical mass, the empirical subscripts are multiplied by that factor. This is a convenient way to connect elemental analysis with a real molecular formula. Results are estimates, so rounded composition data can create small differences. Always use sensible significant figures and check that the final ratio matches the chemistry of the problem.