What this calculator calculates
Enter an Actual yield and a Theoretical yield. The calculator applies % Yield = (Actual yield / Theoretical yield) × 100 and displays one Percent yield statistic, the formula, the supplied values, and the final calculation.
Formula and supported units
Use milligrams (mg), grams (g), kilograms (kg), or moles (mol) in either field. Both fields must use the same unit family: mass units (mg, g, or kg) together, or mol in both fields.
Mass units can differ between the fields because the calculator normalizes them internally. It does not convert mass to moles, so a mass value and a mole value cannot be used together.
How to use the Percent Yield Calculator
- Enter a value in Actual yield and choose its Unit.
- Enter a value in Theoretical yield and choose its Unit.
- Keep both units in the same family:
mg/g/kg, ormolfor both. - Click Calculate. A valid result shows the Percent yield statistic and three steps: the formula, the supplied values, and the final calculation.
- Click Copy result to copy the generated plain-text result, or click Download result (.txt) to save it as a text file.
- Click Reset to clear both fields, restore both units to grams, and hide the error and result.
Input validation and errors
Both values must be greater than zero. Empty fields and invalid numeric text show an error and hide the result. The fields accept decimal notation with an optional leading minus sign; scientific notation and comma-formatted values are not accepted. Each entered value must have an absolute value no greater than 1e12.
Using a mass unit for one field and mol for the other also shows an error. The calculator cannot convert between those families because it does not have a molar mass.
What the calculator does not do
- Balance chemical equations.
- Determine the limiting reagent.
- Calculate theoretical yield from a reaction.
- Look up molar masses or convert between mass and moles.
- Cap or flag results above 100%; it reports the calculated value.
Calculation scope and data handling
The calculator performs the arithmetic locally in the browser. This applies to the calculator inputs and calculation only; the page also includes separate subscription and sharing features.
Frequently Asked Questions
What is the percent yield formula?
Percent yield = (Actual yield / Theoretical yield) x 100. Actual yield is the amount of product actually obtained from a reaction, and theoretical yield is the maximum amount predicted by stoichiometry.
Can percent yield be over 100%?
Mathematically yes if actual yield exceeds theoretical yield, though in practice this usually indicates impurities, residual solvent, or measurement error rather than a true yield above the stoichiometric maximum. This calculator reports the value exactly as computed and does not cap it or flag it as an error.
What units does this calculator support?
Actual and theoretical yield can each be entered in milligrams (mg), grams (g), kilograms (kg), or moles (mol). Both values must use the same unit family - mass-based (mg, g, kg) or moles - so the ratio stays meaningful.
Does this tool calculate theoretical yield for me from a reaction?
No. It performs a deterministic percent-yield calculation from the actual and theoretical yield values you provide. It does not look up molar masses, balance equations, or infer a theoretical yield from stoichiometry - you supply both values.