Percent Yield Calculator

Percent yield is a measure of how efficient a chemical reaction was in practice, calculated as the actual yield obtained in the lab divided by the theoretical yield predicted by stoichiometry, multiplied by 100. A percent yield of 86.5% means the reaction produced 86.5% of the maximum possible product.

Percent Yield = (Actual Yield ÷ Theoretical Yield) × 100%. Actual yield is the amount of product you actually isolated and measured. Theoretical yield is the maximum amount predicted from the balanced chemical equation, assuming the limiting reagent is fully converted with no losses.

Theoretical yield is the maximum amount of product a reaction could produce, calculated from stoichiometry assuming perfect conditions and no losses. Actual yield is the amount you actually measure after running the reaction and purifying the product. Actual yield is almost always lower than theoretical yield due to side reactions, incomplete conversion, and losses during workup.

Yes, and it does not mean your inputs are wrong. A percent yield over 100% usually indicates the isolated product contains impurities, such as residual solvent, unreacted starting material, or moisture, that add extra mass without being the pure target compound. It can also result from a measurement or calculation error in the theoretical yield. Either way, the calculation itself is still valid.

Real reactions rarely achieve 100% yield because of side reactions that consume reactants into unwanted products, reactions that do not go to completion (chemical equilibrium), and physical losses during transfer, filtration, and purification steps. A yield of 70 to 90% is considered good for many organic syntheses; simple inorganic reactions can exceed 95%.

The Stoichiometry Calculator computes theoretical yield FROM a balanced chemical equation and known reactant masses, working forward from the reaction. This Percent Yield Calculator instead starts from two numbers you already know, an actual yield measured in the lab and a theoretical yield you already calculated or were given, and compares them to find the efficiency percentage. Many students arrive at this calculator with both numbers already in hand from a lab report.

Rearrange the formula: Actual Yield = (Percent Yield ÷ 100) × Theoretical Yield. Select Find Actual Yield mode, enter the percent yield and theoretical yield, and the calculator applies this formula directly. Example: a 75% yield reaction with a theoretical yield of 80 g produces an actual yield of 60 g.

Rearrange the formula: Theoretical Yield = Actual Yield ÷ (Percent Yield ÷ 100). Select Find Theoretical Yield mode, enter the percent yield and actual yield. Example: if a reaction achieved 90% yield and produced 36 g of actual product, the theoretical yield was 36 ÷ 0.9 = 40 g.

It depends heavily on the reaction type. Simple, single-step inorganic reactions (like precipitation or acid-base neutralization) commonly achieve 90 to 100% yield. Complex multi-step organic syntheses, especially those involving purification by chromatography or recrystallization, often achieve 60 to 85% per step, and much lower overall across many steps, since yields multiply.

No, as long as actual yield and theoretical yield are both expressed in the same unit. Percent yield is a ratio, so grams-to-grams and moles-to-moles both give the identical percentage. The unit selector on this calculator is for display labeling only; it does not perform any unit conversion.

Common causes include incomplete reactions (the reaction did not reach completion before workup), competing side reactions consuming reactants, product loss during transfer between containers, loss during filtration or washing steps, and loss during recrystallization or chromatographic purification. Careful technique and optimized reaction conditions both improve percent yield.

In industrial manufacturing, percent yield directly determines production cost and efficiency. Even small improvements in percent yield across a large-scale process (pharmaceuticals, polymers, fine chemicals) translate into significant savings in raw materials, energy, and waste disposal, which is why process chemists spend substantial effort optimizing reaction conditions to maximize yield.