Theoretical Yield Calculator

Theoretical yield is the maximum amount of product that could be produced in a chemical reaction, assuming perfect conditions and complete conversion of the limiting reagent. It is calculated using stoichiometry from the balanced chemical equation and represents an upper bound — real reactions almost always produce less due to side reactions, incomplete conversion, or losses during isolation.

Use the formula: theoretical yield = product molecular weight × (moles of limiting reagent × product stoichiometry / limiting reagent stoichiometry). First convert your limiting reagent mass to moles by dividing by its molecular weight, then multiply by the mole ratio (product stoichiometry ÷ limiting reagent stoichiometry), and finally multiply by the product's molecular weight to get mass in grams.

The limiting reagent is the reactant that is completely consumed first, stopping the reaction from proceeding further. Theoretical yield can only be calculated based on the limiting reagent because once it runs out, no more product can form — regardless of how much of the other reactants remain.

No. The limiting reactant is the reactant that runs out first and controls how much product forms. The theoretical yield is the maximum mass of product that can be produced based on the amount of the limiting reactant available. They are related but distinct concepts.

Theoretical yield is the calculated maximum product assuming a perfect reaction. Actual yield is the amount of product you physically obtain in the lab. Actual yield is almost always less than theoretical yield due to incomplete reactions, competing side reactions, and product lost during purification. The ratio of actual to theoretical yield (×100) gives percent yield.

Percent yield measures how efficiently a reaction was carried out: percent yield = (actual yield ÷ theoretical yield) × 100%. A percent yield of 100% would mean no product was lost, which is essentially impossible in practice. Knowing the theoretical yield is the first step in calculating percent yield.

Stoichiometric coefficients are the numbers placed in front of each reactant and product in a balanced chemical equation. For example, in N₂ + 3H₂ → 2NH₃, the coefficient for N₂ is 1, for H₂ is 3, and for NH₃ is 2. They tell you the molar ratio in which substances react and are produced.

Using N₂ + 3H₂ → 2NH₃: moles of N₂ = 10 g ÷ 28.014 g/mol ≈ 0.357 mol. Moles of NH₃ = 0.357 × (2/1) = 0.714 mol. Theoretical yield = 0.714 mol × 17.031 g/mol ≈ 12.16 g of NH₃. This example is pre-loaded in the calculator above.