Compare moles divided by balanced-equation coefficients to find the limiting reactant without pretending to balance the equation for you.
Enter amounts already converted to moles, or enter grams plus molar mass. Coefficients must come from a balanced chemical equation; this tool does not balance reactions.
Cross-check reaction extent, limiting reactant, excess remaining and optional theoretical product yield from balanced coefficients.
Limiting-reagent work depends on stoichiometric coefficients, not just the masses of the reactants. Convert each amount to moles, compare the amount available per coefficient, and identify the smallest reaction extent. An unbalanced reaction or wrong molar mass will make every downstream yield value wrong.
Use the tool first, then apply these checks to verify inputs, interpret the result, and hand it off without displacing the primary workflow.
The limiting reagent is determined by stoichiometric coefficients, not by which reactant has the smaller mass or mole count. Confirm the balanced equation first, then convert each supplied amount to moles and divide by its coefficient. The smallest stoichiometric extent identifies the limiting reactant under the stated reaction model.
A mass input must be divided by the molar mass of that exact substance before stoichiometric comparison. Hydrates, solvates, salts, isotopic compositions, and formula-unit conventions can change molar mass. Keep the chemical formula and molar mass used in the calculation with the result so another person can audit the conversion.
The limiting reactant sets the maximum theoretical amount of product for a complete reaction. Real isolated yield can be lower because of equilibrium, side reactions, transfer loss, incomplete conversion, or purification. Do not treat the theoretical result as a guaranteed laboratory output; apply a measured or justified percent yield separately when needed.
Use enough internal precision through mole and ratio calculations, then round the final reported quantity to a level supported by the measured inputs. Premature rounding can change which reagent appears limiting when two stoichiometric extents are close. If the result is near a tie, show the unrounded extents as a verification check.
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