Limiting Reactant Calculator
For a reaction with two reactants A and B in ratio a:b, find which one runs out first.
Result
How to use this calculator
- Enter moles of A and B.
- Enter their coefficients from the balanced equation.
- Read which is limiting and how much of each is consumed/leftover.
About this calculator
In any chemical reaction with multiple reactants, one will run out first — the limiting reactant. To find it, divide each reactant's moles by its stoichiometric coefficient. Whichever ratio is smallest is limiting; the others are in excess. The reaction yield is determined entirely by the limiting reactant.
Frequently asked
What if I have 3+ reactants?+
What does "perfectly stoichiometric" mean?+
Why divide by coefficient?+
How to use limiting-reactant in yield calculations?+
What about catalysts?+
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