Percent Yield Calculator

Percent yield compares the actual amount of product obtained from a reaction to the theoretical maximum predicted by stoichiometry. It is a measure of how efficient the reaction was under the conditions used.

% yield = (actual yield / theoretical yield) x 100. Both yields must be in the same unit (grams, moles, etc.) for the ratio to be meaningful.

Identify the limiting reactant on the balanced equation, convert its mass to moles, use mole ratios to find moles of product, then convert back to mass with the product's molar mass.

Mathematically it can be greater than 100, but in practice that almost always means the product was wet, contained unreacted starting material, or was contaminated with a side product. Re-dry and re-weigh before drawing conclusions.

Real reactions lose product to transfer steps, side reactions, evaporation, incomplete reaction, and purification. A yield around 70 to 90 percent is common for many synthetic procedures.

Whatever unit you measured in, as long as both the actual and theoretical yields are in the same unit. Grams is the most common; moles works when you used mole-based stoichiometry directly.