Percent Yield Calculator
Above 100 percent means the product is wet or impure, not that the chemistry over-performed.
The formula
theoretical = (mass / molar mass) * ratio * product molar mass ; percent = actual / theoretical * 100
Theoretical, actual, percent
The theoretical yield is what the balanced equation permits if every molecule of the limiting reactant converts. The actual yield is what comes out of the flask after transfers, side reactions and losses on the filter paper. The percent yield is the second divided by the first, and a figure above 100 % means the product is wet or impure rather than that the chemistry over-performed.
Yield is not atom economy
A reaction can run at a perfect 100 % yield and still send most of its mass to waste, because the yield only measures how much of the possible product was recovered. Atom economy asks a different question: of all the mass fed in, how much appears in the product you wanted? An addition reaction can reach 100 %; a substitution never does.
Balanced first, always
Every quantity on this page depends on a balanced equation. The coefficients set the molar ratio, the ratio sets the theoretical yield, and the yield is what the percentage is measured against. An unbalanced equation does not give a slightly wrong answer — it gives an answer to a different question.