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What does this calculator estimate?
A percent yield calculator compares the product you actually obtained to the theoretical maximum. Enter the actual and theoretical yields to see the percentage.
- Percent yield = actual ÷ theoretical × 100
- Real yields are usually below 100%
- Above 100% suggests impurities or measurement error
What percent yield tells you
Percent yield measures how efficiently a reaction converted reactants to the desired product: the actual mass collected divided by the theoretical maximum from stoichiometry. It reflects losses from incomplete reaction, side products, and handling.
Limitations to watch for
The estimate assumes the theoretical yield was computed correctly from the limiting reagent. A result above 100% usually means wet, impure, or contaminated product — not a miracle. Percent yield doesn't measure purity on its own.
How to use it in practice
Compute the theoretical yield from the limiting reagent first, then weigh the dried product carefully. Use the percent yield to compare runs and troubleshoot: low yields point to side reactions or losses during workup.
['Enter the actual yield (what you collected).', 'Enter the theoretical yield (from stoichiometry).', 'The tool computes the percentage and flags values above 100%.']
What percent yield measures
Percent yield compares actual product to theoretical: actual ÷ theoretical × 100. A reaction expected to produce 10 g that yields 8 g has 80 percent yield. It is the core efficiency metric in chemistry.
Why yield falls short
Side reactions, incomplete conversions, losses in purification, and measurement error all reduce yield. A 90+ percent yield is excellent; 60–80 percent is common for multistep syntheses; below 50 percent warrants process review.
Theoretical yield from stoichiometry
Theoretical yield comes from the balanced equation and the limiting reagent: moles of limiting reagent × molar ratio × product molar mass. The calculator accepts the theoretical value; the stoichiometry step is the prerequisite.
A worked example
A reaction with theoretical yield 12.5 g produces 10.3 g: percent yield = 10.3 ÷ 12.5 × 100 = 82.4 percent. The calculator returns the percentage and flags the quality zone.
Using yield in planning
Percent yield scales a recipe: to recover 20 g at 80 percent yield, plan for 25 g theoretical. The calculator's reverse view returns the theoretical needed for a target recovery.
How this calculator works
Formula
Percent yield = (actual yield ÷ theoretical yield) × 100. The theoretical yield is the maximum product mass predicted by stoichiometry; the actual yield is what the experiment produced.
Worked example
A reaction with a theoretical yield of 10.0 g that actually produced 8.5 g has a percent yield of 8.5 ÷ 10.0 × 100 = 85%.
Assumptions to verify
- The theoretical yield is correct.
- The product was dried and weighed accurately.
- The reaction follows the expected stoichiometry.
Frequently asked questions
What is percent yield?
Actual yield ÷ theoretical yield × 100 — how much product you got versus the maximum possible from stoichiometry.
How do I calculate it?
Divide the actual product mass by the theoretical yield and multiply by 100. 8.5 g of 10.0 g theoretical = 85%.
What is theoretical yield?
The maximum product mass predicted by the balanced equation from the limiting reagent, assuming 100% efficiency.
Why is my yield below 100%?
Incomplete reactions, side products, losses during transfer and purification, and product left in glassware all reduce actual yield.
What does a yield above 100% mean?
Usually the product is wet, impure, or weighed with contamination — or the theoretical yield was miscalculated.
Is a higher yield always better?
Generally yes, but purity matters too — a high yield of impure product isn't a success. Percent yield and purity are separate measures.
How is yield used in industry?
Process chemists optimize conditions to maximize yield and minimize waste, since raw materials and purification dominate cost.
How do I calculate theoretical yield?
From the balanced equation and the limiting reagent's moles.
What is a good percent yield?
90%+ is excellent; 60–80% is common in multistep work; below 50% needs review.
How do I plan for yield losses?
Divide the target recovery by the expected yield fraction.
Cite this tool
BoringToolsKit. “Percent Yield Calculator.” boringtoolskit.com/percent-yield-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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