Frequently Asked Questions

Percent yield = (Actual Yield ÷ Theoretical Yield) × 100. Actual yield is the amount of product you actually recover from an experiment; theoretical yield is the maximum amount predicted by the balanced equation and your limiting reagent.

Yes, though it usually indicates an error rather than a real result. Common causes are impure product (unreacted starting material or solvent still weighed in), or a measurement mistake.

Side reactions, incomplete reactions, and product lost during transfer, filtration, or purification all reduce the actual yield below the theoretical maximum.

Use stoichiometry: convert the limiting reagent's mass to moles, use the balanced equation's mole ratio to find moles of product, then convert to grams using the product's molar mass.

The tool is unit-agnostic for mass — enter actual and theoretical yield in the same unit (grams, milligrams, or moles) and the percent yield will be correct regardless of which unit you use.

Yes. Leave the actual yield field blank, enter theoretical yield and the percent yield you want to hit, and the calculator solves for the actual yield.

Yes. Leave the theoretical yield field blank, enter the actual yield and percent yield, and the calculator solves for theoretical yield.

Generally yes for efficiency, but purity matters too. A high percent yield with impure product is often worse than a lower yield of pure product.

No. Percent yield measures how much product you obtained relative to the maximum possible, not how fast the reaction occurred.

Yes, completely free with no sign-up, and it runs entirely in your browser.