percent yield = actual ÷ theoretical × 100 — fill in every field except the one you want; the empty field is solved for.
%
Percent yield (%) = 84 %
- Rearrange:
% = actual ÷ theoretical × 100 - Substitute:
(4.2 g) ÷ (5 g) × 100=84 %
How it works
Percent yield = actual yield ÷ theoretical yield × 100. Both masses are converted to grams first, so you can enter them in different units. To find the theoretical yield itself from a balanced equation and reactant amounts, use the limiting reagent or stoichiometry calculator.
Yields below 100 % are normal: reactions may not go to completion, side reactions form other products, and some product is lost during filtering, transferring and purifying. A yield above 100 % usually means the product is still wet or impure.
Frequently asked questions
- How do I calculate percent yield?
- Divide the actual yield by the theoretical yield and multiply by 100. If you expected 5.0 g and got 4.2 g, the percent yield is 4.2 ÷ 5.0 × 100 = 84 %.
- What is theoretical yield?
- The maximum mass of product that could form if the limiting reagent reacted completely, calculated from the balanced equation.
- Can percent yield be over 100 %?
- Not for a pure, dry product. A result above 100 % points to an error — usually water or solvent still in the sample, or impurities.
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