Work out the maximum amount of product a reaction can give. Enter the limiting reagent (as a formula or molar mass), how much you have, the coefficients from the balanced equation and the product, and get the theoretical yield in grams and moles, plus your percent yield if you measured one.
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Limiting reagent
Desired product
g
Enter your measured product mass to get the percent yield
Enter your values to see the result.
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How to use the Theoretical Yield Calculator
Enter the limiting reagent as a formula (C7H6O3) or a molar mass (138.12).
Enter its amount and coefficient from the balanced equation.
Enter the product formula or molar mass and its coefficient.
Optionally type your actual yield to get the percent yield.
Read the theoretical yield and the table of expected yields.
Theoretical yield formula
Yield (g) = (mreagent ÷ Mreagent) × (b ÷ a) × Mproduct, where a is the coefficient of the limiting reagent and b the coefficient of the product in the balanced equation aA + … → bB + …
Reaction
Limiting reagent
Ratio
Theoretical yield
C₇H₆O₃ + C₄H₆O₃ → C₉H₈O₄ + CH₃COOH
2.00 g salicylic acid
1 : 1
2.61 g aspirin
N₂ + 3H₂ → 2NH₃
28.0 g N₂
1 : 2
34.05 g NH₃
Fe₂O₃ + 3CO → 2Fe + 3CO₂
1.00 kg Fe₂O₃
1 : 2
699.4 g Fe
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
0.5 mol glucose
1 : 6
132.0 g CO₂
Tips for getting it right
Always start from a balanced equation; the coefficients set the mole ratio.
Use the limiting reagent, not the reagent you have the most grams of.
For hydrates, include the water in the formula (e.g. CuSO4·5H2O) because it changes the molar mass.
Report the answer with the same number of significant figures as your least precise measurement.
Frequently asked questions
What is theoretical yield?
It is the maximum mass of product that can form from the limiting reagent if the reaction goes to completion with no losses. It is calculated purely from stoichiometry: the balanced equation and molar masses.
How do I calculate the theoretical yield of aspirin?
Salicylic acid (C₇H₆O₃, 138.12 g/mol) gives aspirin (C₉H₈O₄, 180.16 g/mol) 1:1. From 2.00 g: 2.00 ÷ 138.12 = 0.01448 mol, so the theoretical yield is 0.01448 × 180.16 = 2.61 g.
How do I know which reactant is the limiting reagent?
Divide the moles of each reactant by its coefficient; the smallest result is limiting. If you are not sure, use the Limiting Reactant Calculator, which checks all reactants at once.
What is the difference between theoretical, actual and percent yield?
Theoretical yield is the calculated maximum. Actual yield is what you really obtain in the lab. Percent yield = actual ÷ theoretical × 100%.
Can the percent yield be over 100%?
Not for a pure, dry product. Values above 100% usually mean the product still contains solvent or water, or is contaminated, or the masses were measured incorrectly.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.