Percent Yield Calculator
Calculate the percent yield of a reaction from the actual mass obtained and the theoretical maximum, with the loss.
How much of the possible product you actually got.
How the percent yield calculator works
Theoretical yield is what stoichiometry predicts if every molecule of the limiting reagent reacts and everything is recovered; actual yield is what you weighed. Percent yield = actual ÷ theoretical × 100. Yields above 100% mean the product is wet or impure.
Formula: % yield = actual ÷ theoretical × 100
Worked examples
| Inputs | Percent yield | Note |
|---|---|---|
| 8.2 g obtained of a possible 10.5 g | 78.1% | 78.1% |
| 4.9 g of 5.0 g | 98% | 98% |
| 11 g of 10.5 g | 104.76% | over 100% — wet product |
FAQFrequently asked questions
How do I find the theoretical yield?
Convert the limiting reagent to moles, apply the mole ratio from the balanced equation, and convert the product moles to grams with its molar mass.
What is a good percent yield?
It depends on the reaction: simple precipitations reach 90%+; organic syntheses often give 40–80% per step, which compounds over a route.
Why is my yield over 100%?
Residual solvent or water, impurities, or a weighing error. Dry the product properly and check the balance.
What is atom economy?
A different measure: the share of reactant mass that ends up in the desired product according to the equation, regardless of how well the reaction was run.
Where these figures come from
- IUPAC — Standard atomic weights (2021 conventional values) — the molar-mass table
- NIST — CODATA 2018 fundamental physical constants — Avogadro constant, gas constant, speed of light
- NIST Chemistry WebBook — thermochemical data
- CSIRO — Australia's national science agency
Last checked: September 2026. Atomic masses are the IUPAC conventional values; constants are CODATA 2018; equations are the standard textbook forms.