Formula
Percent yield = actual yield ÷ theoretical yield × 100. Yield difference = actual yield − theoretical yield. Unrecovered amount = max(0, theoretical yield − actual yield). Target actual yield = theoretical yield × target yield percent ÷ 100.
Math & Statistics
Percent Yield Calculator
Calculate chemistry percent yield from actual yield and theoretical yield, with mass basis, loss amount, signed difference, formula, caveats and a printable lab worksheet record.
Calculator
Working calculator
Live result84% yield8.4 ÷ 10 × 100 = 84% exact · rounded to 0.01% · -1.6 g vs theoretical (below theoretical yield) · unrecovered amount 1.6 g · target 90% needs 9 g, so this result is -0.6 g vs target
Formula used
Percent yield = actual yield ÷ theoretical yield × 100. Yield difference = actual yield − theoretical yield. Unrecovered amount = max(0, theoretical yield − actual yield). Target actual yield = theoretical yield × target yield percent ÷ 100.
This is the method behind the answer, so the result can be checked rather than simply trusted.Visual grid
This number is one point on a larger pattern
Percent Yield is not just a final answer. It is a step on a line: before and after, input and output, assumption and result.
Micro-timehours, minutes, shiftsHuman scaledays, weeks, projectsMacro-timemonths, years, calendars
InputFormulaResult
84% yieldCalculationTime keeps the path visible: the input, the method and the final number belong together.
CalculationTime
Percent Yield Calculation Report
84% yield8.4 ÷ 10 × 100 = 84% exact · rounded to 0.01% · -1.6 g vs theoretical (below theoretical yield) · unrecovered amount 1.6 g · target 90% needs 9 g, so this result is -0.6 g vs target
Inputs
- Actual yield
- 8.4 g
- Theoretical yield
- 10 g
- Target yield
- 90 % optional
- Percent rounding increment
- 0.01 %
Method
Percent yield = actual yield ÷ theoretical yield × 100. Yield difference = actual yield − theoretical yield. Unrecovered amount = max(0, theoretical yield − actual yield). Target actual yield = theoretical yield × target yield percent ÷ 100.
- If the actual yield is 8.4 g and the theoretical yield is 10 g, percent yield = 8.4 ÷ 10 × 100 = 84.00%. The unrecovered amount is 1.6 g. Against a 90% target, the target actual yield would be 9.0 g, so the result is 0.6 g below target.
Assumptions
- Actual yield and theoretical yield must use the same unit and substance basis, such as grams of the purified product.
- Theoretical yield is the denominator and must be greater than zero.
- A percent yield above 100% can happen in real notes when the product is wet, impure, contaminated, weighed incorrectly or when the theoretical-yield setup is wrong.
- The calculator performs arithmetic only; it does not validate stoichiometry, purity, limiting reactants, significant figures, lab safety or process compliance.
Notes
Use this space on the printed report for client, supplier, classroom, job-location, measurement, quote or approval notes.
Worked example
If the actual yield is 8.4 g and the theoretical yield is 10 g, percent yield = 8.4 ÷ 10 × 100 = 84.00%. The unrecovered amount is 1.6 g. Against a 90% target, the target actual yield would be 9.0 g, so the result is 0.6 g below target.
Professional note
Master’s Tip: print the substance name, limiting-reactant note and whether the mass was dry or wet beside the percent yield. The arithmetic can look precise even when the product basis, purity or weighing step is the real source of error.
Regional and unit assumptions
Standard or basis: general chemistry percent-yield arithmetic using actual yield divided by theoretical yield. Units are entered as grams by default, but any matching mass or amount unit can be used if actual and theoretical yield share the same basis.
Assumptions and limitations
- Actual yield and theoretical yield must use the same unit and substance basis, such as grams of the purified product.
- Theoretical yield is the denominator and must be greater than zero.
- A percent yield above 100% can happen in real notes when the product is wet, impure, contaminated, weighed incorrectly or when the theoretical-yield setup is wrong.
- The calculator performs arithmetic only; it does not validate stoichiometry, purity, limiting reactants, significant figures, lab safety or process compliance.
- For graded lab reports, regulated production or safety decisions, follow the instructor, laboratory method, standard operating procedure or professional review.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Percent yield = actual yield ÷ theoretical yield × 100. Yield difference = actual yield − theoretical yield. Unrecovered amount = max(0, theoretical yield − actual yield). Target actual yield = theoretical yield × target yield percent ÷ 100.
Standard or basis
Standard or basis: general chemistry percent-yield arithmetic using actual yield divided by theoretical yield. Units are entered as grams by default, but any matching mass or amount unit can be used if actual and theoretical yield share the same basis.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: print the substance name, limiting-reactant note and whether the mass was dry or wet beside the percent yield. The arithmetic can look precise even when the product basis, purity or weighing step is the real source of error.
Related calculators
Questions
How do you calculate percent yield?
Divide actual yield by theoretical yield, then multiply by 100. For example, 8.4 g ÷ 10 g × 100 = 84%.
What is theoretical yield?
Theoretical yield is the maximum amount expected from the balanced reaction or problem setup, usually based on the limiting reactant.
Can percent yield be over 100%?
Yes in recorded results, but it usually signals wet product, impurities, contamination, weighing error, side material or a mistake in the theoretical-yield setup.
Is percent yield the same as percent error?
No. Percent yield compares actual product recovered with theoretical product expected. Percent error compares a measured value with an accepted reference value.
What should I print for a percent yield lab worksheet?
Print actual yield, theoretical yield, percent yield, unrecovered amount, target comparison, formula, assumptions, page URL, date and notes about substance, limiting reactant, purity and drying.
Calculation note
Percent yield is a bridge between balanced-reaction arithmetic and what was actually recovered. It is useful because it compresses a lab result into one percentage, but the source masses and method notes decide whether that percentage is trustworthy.
Yield depends on the denominator
Theoretical yield is the comparison base. If the limiting reactant, molar mass, purity or stoichiometry setup is wrong, the percent yield can be wrong even when the final division is correct.
Above 100% is a warning, not a bonus
A result above 100% usually means the recovered product includes something extra, such as solvent, water, impurities or measurement error. The calculator keeps signed difference visible so that warning is not hidden.
Printable lab notes protect the method
A useful percent-yield record should include actual yield, theoretical yield, product identity, formula, assumptions and method notes. That makes the number easier to audit in class, a lab notebook or a process review.
Sources and further readingOpenStax Chemistry 2e — Stoichiometry and yieldChem LibreTexts — Theoretical and Percent Yield