Percent Yield Calculator
Percent yield and theoretical yield from the limiting reactant.
About this tool
Enter the limiting reactant's mass and molar mass, the coefficients from the balanced equation and the product's molar mass to get the theoretical yield. Then add the actual yield, or type a theoretical yield directly, to get the percent yield.
Calculating yield
Percent yield = actual yield รท theoretical yield ร 100. The theoretical yield is the most product the limiting reactant can make. Convert the reactant's mass to moles (mass รท molar mass), scale by the mole ratio from the balanced equation (product coefficient รท reactant coefficient), and convert back to grams with the product's molar mass. For example, heating 10 g of calcium carbonate (CaCOโ โ CaO + COโ, molar mass 100.09 g/mol) produces at most 0.0999 mol, or 5.603 g, of calcium oxide (56.08 g/mol). If 5.0 g is actually collected, the yield is 89.2%. Real yields fall short because of incomplete reactions, side reactions and product lost during filtering, washing and transfer. A yield above 100% almost always means the product is still wet or contaminated, or the theoretical yield was calculated from the wrong reactant. Honest limits: the tool assumes you've balanced the equation and identified the limiting reactant (the one that gives the least product). The molar mass calculator and the chemical equation balancer are related.
Frequently asked questions
How do I calculate percent yield?
Divide the actual yield by the theoretical yield and multiply by 100.
How do I find theoretical yield?
Convert the limiting reactant to moles, multiply by the mole ratio from the balanced equation, then multiply by the product's molar mass.
Can percent yield be over 100%?
Not genuinely. Over 100% usually means impurities, leftover solvent or a calculation error.
What is a limiting reactant?
The reactant that runs out first, which limits how much product can form.
Is my data sent anywhere?
No. Everything is calculated in your browser, and nothing is stored or sent.