Percent Yield
Efficiency of a chemical reaction.
Formula
Live Calculator
MembersVariables
Example
Getting 8 g when 10 g was expected is an 80% yield.
How it works
Percent yield compares how much product you actually obtained from a reaction with the maximum amount that stoichiometry says should be possible. It works by taking the ratio of actual to theoretical product, then multiplying by 100 so the result is a percentage. A value below 100% is common because reactions can be incomplete, side reactions can occur, or product can be lost during purification and transfer.
When to use it
Use this formula in chemistry labs and stoichiometry problems whenever you know the predicted amount of product from balanced equations and need to judge how efficient the reaction was. It is especially useful in synthesis, limiting-reactant calculations, and evaluating experimental technique.
Worked example, step by step
A reaction is predicted to produce 25.0 g of product. The experiment actually produces 19.5 g. Percent yield = (actual / theoretical) × 100 Percent yield = (19.5 g / 25.0 g) × 100 Percent yield = 0.78 × 100 Percent yield = 78% So the reaction had a yield of 78%.
Common mistakes to avoid
- Reversing the formula and dividing theoretical by actual
- Using measured mass of reactants instead of measured mass of product for the actual yield
- Forgetting to multiply by 100 to convert the ratio into a percent
Did You Know?
Real chemical reactions rarely hit 100% yield — side reactions and losses always take a cut.
Share this formula
More in Chemistry
View allIdeal Gas Law
IntermediateRelates pressure, volume, moles and temperature of a gas.
Molarity
BasicConcentration in moles of solute per litre of solution.
Moles from Mass
BasicNumber of moles from mass and molar mass.
pH
BasicAcidity from hydrogen-ion concentration.
pOH
BasicBasicity from hydroxide-ion concentration.
Henderson–Hasselbalch
AdvancedpH of a buffer solution.