Molar Ratio Calculator

A molar ratio compares the amounts of substances that participate in a balanced chemical reaction. The coefficients written before formulas in the equation provide that ratio. For example, a coefficient relationship of two to three means that every two moles of the known substance correspond to three moles of the target substance, assuming the reaction follows the equation completely. This calculator multiplies the known amount in moles by the target coefficient and divides by the known substance coefficient. Coefficients must come from a correctly balanced equation and are entered as positive whole numbers. An omitted coefficient in a written equation means one. The known amount itself may be a decimal because laboratory samples commonly contain fractions of a mole. Coefficients are not subscripts: a coefficient counts complete formula units or moles, while a subscript describes the atoms within one formula unit. Before using the ratio, identify the known and target species explicitly. Copy each coefficient from the same balanced equation, even if the substances occur on opposite sides of the reaction arrow. The direction does not change the arithmetic; only the coefficient relationship matters. For a reaction where two moles of a reactant yield three moles of a product, two known moles correspond to three target moles. Half a known mole would correspond to three quarters of a target mole under the same ratio. The result is a theoretical stoichiometric amount. It assumes enough of every other reactant is available and that the reaction proceeds according to the equation. In real experiments, limiting reactants, incomplete conversion, side reactions, purity, and product loss can reduce the amount actually obtained. If several reactants are supplied, calculate the possible product from each one to identify the limiting reactant. Then apply percent yield separately when estimating an experimental outcome. This tool deliberately focuses on the core mole-to-mole conversion, making it useful as an intermediate step after converting mass, gas volume, or solution concentration to moles and before converting the target moles into the desired laboratory unit. A useful written solution includes units at every stage and labels each coefficient with its substance. Canceling the known substance's mole unit before interpreting the target helps expose inverted ratios. This simple dimensional check prevents a common mistake and makes the calculation easier to review.