Percent Yield Calculator
Percent yield compares what you actually got to what the reaction could have made. Enter both amounts and it works out the percentage in one step.
Percent yield is what you actually got divided by what the reaction could have produced, times 100. Recover 8.4 g out of a possible 10 g and you're at 84% — a solid result for a real bench reaction.
Percent yield
84%
Amount short of theoretical
1.6
Keep both yields in the same units — grams with grams, or moles with moles. A figure above 100% usually means leftover solvent or an impurity padding the mass, not extra product.
How it works
Percent yield rates how well a reaction went: actual yield divided by theoretical yield, times 100. The theoretical yield is the most you could possibly make from your limiting reactant, on paper.
Type in the amount you actually recovered and the theoretical amount, keeping both in the same units — grams with grams, or moles with moles. Recover 8.4 g of a possible 10 g and the tool shows 84%.
It also tells you how far short you fell. If the theoretical yield is zero or blank the percentage can't be defined, so the tool shows a dash instead of dividing by zero.
Frequently asked questions
How do I find the theoretical yield?
Start from your balanced equation and the limiting reactant, then use stoichiometry to convert moles of that reactant into moles — and grams — of product. That maximum amount is the theoretical yield.
Can percent yield go over 100%?
In theory no, since you can't make more product than the reactants allow. A figure above 100% almost always means the product still held leftover solvent, water, or an impurity padding its mass.
What counts as a good percent yield?
It depends on the reaction, but anything above about 80% is usually considered strong for bench work. Losses to side reactions, transfers, and purification steps make a perfect 100% rare in practice.