Percent YieldFree online science calculator — instant results, no sign-up
Calculate the percent yield of a chemical reaction.
About the Percent Yield
The Percent Yield calculator compares the actual mass of product recovered from a chemical reaction with its theoretical maximum mass. It reports the percent yield and the mass shortfall labeled Lost. With an actual yield of 18.5 g and a theoretical yield of 22.4 g, the results are 82.59% yield and 3.9 g lost.
- Actual yield (g)
- The measured mass of the product recovered from the reaction, in grams, with a default value of 18.5 g.
- Theoretical yield (g)
- The maximum mass of the same product predicted by reaction stoichiometry and the limiting reactant, in grams, with a default value of 22.4 g.
Formula and method
Y = (m_actual / m_theoretical) × 100%; L = m_theoretical − m_actual. With the default inputs: Y = (18.5 / 22.4) × 100% = 82.59% (rounded); L = 22.4 − 18.5 = 3.9 g.
- YPercent yield of the chemical reaction.
- m_actualActual mass of recovered product in grams.
- m_theoreticalTheoretical maximum mass of that product in grams.
- LMass shortfall in grams, displayed as Lost.
Divide the actual yield by the theoretical yield, then multiply by 100 to express the ratio as a percentage. Subtract the actual yield from the theoretical yield to calculate Lost. For the default inputs, round the percentage to two decimal places to obtain 82.59%, and report the mass difference as 3.9 g.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Actual yield18.5 g
- Theoretical yield22.4 g
Results
- Percent yield82.59%
- Lost3.9 g
How to use the Percent Yield
- 1Determine the theoretical yield for the desired product using the balanced reaction and limiting reactant.
- 2Enter the recovered product mass in Actual yield (g); the default is 18.5 g.
- 3Enter the predicted maximum product mass in Theoretical yield (g); the default is 22.4 g and this value must be greater than zero.
- 4Calculate the results using the actual-to-theoretical mass ratio and the difference between the masses.
- 5Read the Percent yield and Lost rows; the default inputs give 82.59% and 3.9 g, respectively.
Reading your result
Percent yield shows the recovered product mass as a percentage of the theoretical maximum: 82.59% means the actual yield is 82.59% of the predicted yield. Lost shows the difference between theoretical and actual product mass: 3.9 g means that much less product was recovered than predicted. Lost is a product shortfall, not a measurement of total matter lost from the reaction system.
Limitations
Both inputs must describe the same product in grams, actual yield must be nonnegative, and theoretical yield must be positive. This tool does not calculate theoretical yield from reactant quantities or identify the limiting reactant. The comparison assumes a correct theoretical yield and an actual yield representing the intended product rather than wet or impure material. It cannot distinguish incomplete reaction, side reactions, and recovery losses. Displayed decimal places do not establish experimental precision.
Common questions
Why do 18.5 g actual yield and 22.4 g theoretical yield give 82.59%?+
Dividing 18.5 by 22.4 and multiplying by 100 gives approximately 82.5893%, which rounds to 82.59%.
Does Lost = 3.9 g mean 3.9 g of product was spilled?+
No. It is simply 22.4 g minus 18.5 g. The shortfall could reflect incomplete conversion, side reactions, product remaining in solution, or losses during isolation and transfer.
What does a percent yield above 100% mean?+
It means the entered actual yield exceeds the theoretical yield, so Lost is negative. Check for residual solvent, moisture, impurities, weighing errors, or an incorrect theoretical-yield calculation before treating the result as a valid product yield.
Can I use the starting reactant mass as the theoretical yield?+
Not directly. First use the balanced chemical equation, reactant amounts, limiting reactant, and product molar mass to calculate the theoretical mass of the desired product.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.