Percent Yield Calculator
Calculate the percent yield of a chemical reaction — how efficient your synthesis was — by comparing actual to theoretical yield.
How to use this percent yield calculator
- Calculate theoretical yield from stoichiometry: moles of limiting reagent × molar ratio × molar mass of product.
- Weigh your actual collected product.
- Enter both — units must match (both grams, both moles, etc.).
- A result above 100% indicates impurities or measurement error.
Formula
Percent yield = (actual yield ÷ theoretical yield) × 100%. Theoretical yield is the stoichiometric maximum from the limiting reagent.
About the Percent Yield Calculator
Percent yield measures reaction efficiency. Even a 90% yield means 10% of starting material was lost to side reactions, incomplete conversion, or product lost during purification.
Industrial chemists obsess over yield — even 1% improvement in a million-kg/year process saves enormous costs. Green chemistry encourages maximising both yield and atom economy (the fraction of starting material atoms incorporated into the final product).
Frequently asked questions
+Can percent yield exceed 100%?
In theory, no. Above 100% means the product contains impurities (trapped water, side products) or there's a weighing error.
+What is a good percent yield?
Teaching labs: 70–90% is good. Industrial processes: 95%+. Complex organic syntheses: 40–60% may be considered acceptable.
+What is theoretical yield?
The maximum amount of product possible if the limiting reagent reacted completely with 100% efficiency, calculated from stoichiometry.