Limiting Reagent Calculator
Find the limiting reactant, excess reagent, reaction extent, leftover amounts, and theoretical yield from a balanced chemical equation.
Quick answer: convert each reactant to moles, divide by its coefficient, and the smallest value is the limiting reagent.
Set up your stoichiometry calculation
Enter a balanced equation first. Use + between species and -> or = as the arrow.
Product of interest
Quick presets
Load a reaction and enter reactant amounts to calculate the limiting reagent.
How to Find the Limiting Reagent
- Make sure the chemical equation is balanced.
- Convert each reactant amount to moles. For grams, use
moles = grams / molar mass. For solutions, usemoles = M x L. - Divide moles of each reactant by its stoichiometric coefficient.
- The smallest value is the reaction extent and identifies the limiting reagent.
- Use the limiting extent to calculate product moles and leftover excess reactants.
This educational calculator assumes the equation is already balanced and the reaction goes to completion. Real experiments may have side reactions, purity issues, equilibrium limits, or incomplete conversion.