Percent yield calculator
Yield % = (actual ÷ theoretical) × 100 — actual may be zero, theoretical must be positive.
Zero is allowed (a failed or incomplete reaction).
Must be greater than zero — a ratio needs a non-zero denominator.
Fill the two known values — the third is solved for you. Actual and theoretical must share a unit (grams with grams, or moles with moles).
Formula and how to use it
Percent yield compares the product actually isolated with the maximum predicted by stoichiometry: yield % = (actual yield ÷ theoretical yield) × 100. The theoretical yield comes from the limiting reagent's moles and the reaction's stoichiometric ratio; the actual yield is the mass or amount recovered after work-up and purification.
Worked example: if a reaction should produce 10.0 g of product but isolation recovers 8.5 g, the yield is (8.5 ÷ 10.0) × 100 = 85 %. A result above 100 % usually means the product is impure or still wet, the theoretical yield was calculated with the wrong limiting reagent, or a weighing error occurred — mass cannot be created by a reaction.
This calculator solves for percent yield, actual yield, or theoretical yield from the other two. The actual yield may be zero when a reaction fails, but the theoretical yield must be greater than zero. Values above 100 % are accepted and flagged with a warning, so a suspicious result is never silently hidden.