Percent Yield Calculator
Calculate percent, actual or theoretical yield directly, or derive theoretical product mass from a balanced reaction and one reactant.
Percent yield formulas
- Percent yield: actual yield ÷ theoretical yield × 100.
- Actual yield: theoretical yield × percent yield ÷ 100.
- Theoretical yield: actual yield ÷ (percent yield ÷ 100).
- Stoichiometric product moles: reactant moles ÷ reactant coefficient × product coefficient.
- Theoretical product mass: product moles × product molar mass.
Checked examples
| Question | Calculation | Answer |
|---|---|---|
| 8.50 g actual from 10.0 g theoretical | 8.50 ÷ 10.0 × 100 | 85% |
| Actual yield from 25 g at 72% | 25 × 0.72 | 18 g |
| Theoretical yield from 18 g at 72% | 18 ÷ 0.72 | 25 g |
| 5.00 g reactant, 50.0 g/mol | 5.00 ÷ 50.0 | 0.100 mol reactant |
| 2 reactant → 3 product | 0.100 ÷ 2 × 3 | 0.150 mol product |
| 0.150 mol product at 40.0 g/mol | 0.150 × 40.0 | 6.00 g theoretical |
How the stoichiometry mode works
Use coefficients from a balanced chemical equation. The calculator converts the entered reactant mass to moles, applies the product-to-reactant mole ratio and converts product moles to theoretical mass. If an actual product mass is supplied, it also calculates percent yield.
Limits and interpretation
A percent yield above 100% can result from wet or impure product, incomplete drying, measurement error or an incorrect theoretical basis. The stoichiometry mode uses one reactant and assumes it is the limiting reagent with stated purity. It does not identify the limiting reagent among several reactants or model equilibrium, conversion, selectivity, side reactions or product losses.
Frequently asked questions
Can percent yield exceed 100%?
Mathematically yes, but it usually signals extra mass from solvent, water, impurities or measurement and calculation issues.
Do actual and theoretical yield need the same units?
Yes in direct mode. The ratio is valid only when both yields use the same mass or amount unit.
Which reactant should I enter in stoichiometry mode?
Enter the limiting reactant. If multiple reactants are present, determine the limiting reagent before using this mode.