Limiting Reagent Calculator
Determine which reactant is the limiting reagent by comparing mole ratios.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
Can't find what you need?
Request a ToolHow to Use the Limiting Reagent Calculator
Enter the mass, molar mass, and balanced equation coefficient for each of two reactants. The calculator converts to moles, divides by the stoichiometric coefficient, and identifies which reactant produces less product (the limiting reagent).
About the Limiting Reagent Calculator
The limiting reagent determines the maximum yield of a reaction. In any reaction with two or more reactants, one will be consumed first while others remain in excess. Identifying the limiting reagent is essential for calculating theoretical yield and for efficient use of chemicals in the lab.
Frequently Asked Questions
What is a limiting reagent?
The limiting reagent is the reactant that runs out first in a chemical reaction, determining the maximum amount of product formed. The other reactant(s) are "in excess" because some will be left over.
How do I find the limiting reagent?
Convert each reactant mass to moles, then divide each by its coefficient in the balanced equation. The reactant with the smallest result is the limiting reagent.
What happens to the excess reagent?
The excess reagent is not fully consumed. The amount left over can be calculated by subtracting the moles consumed (determined by the limiting reagent and stoichiometry) from the initial moles.