Percent Yield Calculator
Solve for actual yield, theoretical yield, or percent yield using any two known values.
Inputs
Live result
The measured product is 85.32% of the theoretical maximum.
Calculation audit
| Step | Value | Unit | Meaning |
|---|---|---|---|
| Actual yield | 5.58 | g | Measured product mass |
| Theoretical yield | 6.54 | g | Maximum stoichiometric mass |
| Actual ÷ theoretical | 0.853211 | ratio | Fraction of the theoretical maximum recovered |
| Percent yield | 85.32 | % | Ratio expressed as a percentage |
How to use the percent yield calculator
What this calculator does
This calculator connects three quantities used in reaction analysis: Actual yield, Theoretical yield, and Percent yield. Enter any two and it solves the third. Percent yield is an exact mathematical ratio once the two yield values are known, but it does not diagnose why material was lost, whether a product is pure, or whether a reaction is safe or economically attractive. For the underlying chemistry, the theoretical amount must first be established from a balanced equation and the limiting reactant. A concise treatment of that relationship appears in LibreTexts' theoretical yield and percent yield lesson.
When to use it
Use it after a laboratory synthesis to compare isolated product with the stoichiometric maximum, while planning a repeat experiment to estimate the product mass associated with a target percentage, when checking a notebook calculation, or when teaching the difference between measured and theoretical quantities. It is also useful for investigating an apparent yield above 100%, which often signals retained solvent, impurities, incorrect units, or an error in the theoretical-yield calculation rather than exceptional reaction performance.
How to calculate
- The calculator opens with a complete demonstration: 5.58 g actual yield and 6.54 g theoretical yield, giving 85.32%. The Excel workbook for this example is ready immediately.
- Choose the unknown quantity in Solve for. The selected target becomes read-only, while the other two fields accept values.
- Replace the sample values. Use ordinary decimal notation with a period, such as 4.35 or 92. Do not enter scientific notation, commas, unit letters, or negative numbers.
- Read the live result, the three supporting metrics, the formula line, and the calculation audit table. All displayed values come from the same current model.
- Select Download Excel to create a validated workbook containing the current inputs, outputs, formula notes, and audit rows. Reset clears the demonstration and results; Excel remains unavailable until two valid values are supplied again.
Input guide
Solve for is a required selection with three options. Choose Percent yield when both masses are known, Actual yield when a target percentage and theoretical mass are known, or Theoretical yield when actual mass and percentage are known. Actual yield is the nonnegative measured amount of isolated product; enter a plain decimal in grams, for example 5.58. Increasing it raises percent yield or the theoretical yield inferred from a fixed percentage. Theoretical yield is a strictly positive calculated maximum in grams, for example 6.54. Increasing it lowers percent yield when actual yield is fixed. Percent yield is a nonnegative percentage, for example 85.32. Values above 100 are accepted because wet or impure samples can weigh more than the predicted pure product. Zero percent is valid when solving for actual yield, but percent must be greater than zero when it is used to infer theoretical yield, because division by zero is undefined.
Output guide and worked example
The primary result is whichever field you selected in Solve for. Actual yield and Theoretical yield are displayed in grams; Yield gap is theoretical minus actual and may be negative when apparent yield exceeds 100%. The summary pills show the active mode, whether the state is valid, and the unitless actual-to-theoretical ratio. The audit table lists each source value, the ratio, and the final percentage. For the startup example, divide 5.58 g by 6.54 g to obtain 0.853211; multiplying by 100 gives 85.3211%, displayed as 85.32%. The yield gap is 6.54 – 5.58 = 0.96 g. These values match the initial controls, results, table, and workbook.
Formula and interpretation
The core identity is percent yield = (actual yield ÷ theoretical yield) × 100. Rearranging gives actual yield = theoretical yield × percent yield ÷ 100, or theoretical yield = actual yield × 100 ÷ percent yield. The units of the two mass values must match before division. The LibreTexts overview of theoretical and actual yields explains why theoretical yield comes from complete consumption of the limiting reagent, while actual yield is experimentally measured.
A low percentage does not identify a single cause either. Product can remain dissolved, adhere to glassware, decompose, form side products, or be lost during transfer, filtration, washing, drying, or purification. The limiting-reactant and stoichiometric calculation should be checked before interpreting experimental technique; LibreTexts provides a broader limiting reactant, theoretical yield, and percent yield walkthrough.
Common mistakes
- Reversing the fraction. Actual yield belongs in the numerator and theoretical yield in the denominator.
- Mixing grams and milligrams. Convert both values to the same unit first.
- Using reactant mass as actual yield. Actual yield refers to the product collected, not the starting material.
- Rounding the theoretical yield too early. Keep full precision through the stoichiometric calculation, then round the final percentage appropriately.
- Treating percent yield as purity. A large value does not prove the sample is pure; contamination can inflate mass.