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Percent Yield Calculator

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(Actual / Theoretical) × 100.
11 Mass Units.
6-Band Classification.
100% Free.
No Data Stored.

How it Works

01Find Limiting Reagent

Determine which reactant runs out first; calculate moles of product from its stoichiometry

02Compute Theoretical Yield

Theoretical = moles × molar mass × stoichiometric coefficient — the maximum possible mass

03Measure Actual Yield

Weigh the pure, dry product after workup and purification — what you actually isolate

04% Yield = ratio × 100

Divide actual by theoretical and multiply by 100. Compare against 12 reference reactions

What is a Percent Yield Calculator?

Percent yield is the universal report card of every chemical reaction — the single number that tells you how successful your synthesis was, scored on a 0% (got nothing) to 100% (got the maximum theoretically possible) scale. The formula is the very first ratio every chemistry student learns: % Yield = (Actual Yield / Theoretical Yield) × 100. Actual yield is the mass of pure product you actually isolate after the reaction, workup, and purification — what you measure on the balance. Theoretical yield is the maximum mass possible if the reaction proceeded with 100% conversion of the limiting reagent — calculated from stoichiometry. Our Percent Yield Calculator handles both numbers in any of 11 mass units (μg through long ton, both metric and imperial), automatically normalizes to SI grams, and reports the result with 6-band quality classification, material-loss breakdown, and a 12-reaction reference table comparing your result against typical industrial benchmarks.

Just enter the actual mass you isolated and the theoretical maximum, with appropriate units. The calculator divides, multiplies by 100, and reports the percent yield with full unit-conversion traceability. The 6-band classification translates the number into the language chemists actually use: poor < 40% (significant loss, optimization needed), low 40-60% (acceptable for difficult transformations), moderate 60-80% (typical published-paper range), good 80-90% (industrial-grade efficiency), excellent 90-95% (well-optimized catalysis), quantitative ≥ 95% (approaching theoretical maximum, often called "quant"). An anomalous-band flag catches yields above 100% — mathematically possible from the formula but physically impossible by conservation of mass; it always indicates impure product or wrong theoretical calculation.

Designed for general chemistry students learning stoichiometry, organic chemistry students writing up lab reports, synthetic chemists optimizing reaction conditions, process chemists running pilot-plant scale-ups, pharmaceutical chemists evaluating route efficiency for cost-of-goods analysis, and natural-product chemists tracking total-synthesis efficiency across many steps, the tool runs entirely in your browser — no data is stored or transmitted.

Pro Tip: Pair this with our Molar Mass Calculator to compute theoretical yield from limiting-reagent moles, or our Combustion Reaction Calculator for stoichiometry of common combustion processes.

How to Use the Percent Yield Calculator?

Determine the Limiting Reagent: Among all your reactants, identify the one that runs out first based on stoichiometric ratio. For aA + bB → cC: compare moles_A/a vs moles_B/b — whichever is smaller is limiting. Theoretical yield is calculated from THIS reagent's moles.
Calculate Theoretical Yield (mass): Theoretical yield = (moles of limiting reagent) × (stoichiometric ratio of product to limiting reagent) × (molar mass of product). Example: 0.1 mol of bromobenzene + excess Mg → 0.1 mol of phenyl Grignard, which on workup with CO₂ + H₂O gives 0.1 mol of benzoic acid (M = 122.12 g/mol) → theoretical = 12.21 g.
Run the Reaction and Isolate Product: After the reaction, perform workup (quench, extraction, washing) and purification (recrystallization, distillation, chromatography). Dry the product to constant mass. Weigh on a calibrated balance.
Enter Both Yields: Type the actual mass and theoretical mass into the calculator. Pick units independently — actual could be in mg while theoretical is in g, the calculator converts both to SI grams.
Press Calculate: Get the % yield with 6-band quality classification, material loss in grams, loss as % of theoretical, and a comparison against 12 typical reaction yields ranging from acid-base neutralization (~99%) to multi-step natural-product synthesis (0.1-10% overall).
Diagnose Anomalous Yields: If yield comes out > 100%, the calculator flags it as anomalous — physically impossible. Investigate: dry the product more (residual solvent inflates mass), check if the product is impure (recrystallize), or recompute the theoretical yield (you may have used the wrong limiting reagent).

How is percent yield calculated?

Percent yield is the conservation-of-mass scorecard for chemistry — comparing what you got to the maximum nature would allow. Here's the complete framework:

The percent-yield concept dates to Antoine Lavoisier (1789) and the law of conservation of mass — "matter is neither created nor destroyed." The systematic use of yield as a quality metric in synthesis evolved through the 19th-century organic chemistry of Liebig, Wöhler, and Hofmann.

The Formula

For any chemical reaction:

% Yield = (Actual Yield / Theoretical Yield) × 100

Both yields must be in the same units (the calculator handles unit conversion automatically). Result is dimensionless (%).

Computing Theoretical Yield

For a balanced equation aA + bB → cC + dD where A is the limiting reagent:

Theoretical yield (g) = nA × (c/a) × MC

where nA is moles of limiting reagent, c/a is the stoichiometric ratio (moles of C per mole of A), and MC is the molar mass of product C in g/mol.

Identifying the Limiting Reagent

For each reactant, compute its "available reaction equivalents" by dividing moles by its stoichiometric coefficient:

equivA = molesA / coefficientA

The reactant with the SMALLEST equivalents is the limiting reagent. Example: 2 H₂ + O₂ → 2 H₂O. With 4 mol H₂ and 1 mol O₂: equiv(H₂) = 4/2 = 2; equiv(O₂) = 1/1 = 1. O₂ is limiting (smaller equivalents). Maximum H₂O = 1 × (2/1) = 2 mol = 36 g.

Why Real Yield Falls Below 100%

Six common loss mechanisms:

  1. Incomplete reaction: Not all limiting reagent reacts (equilibrium reactions, kinetic limits).
  2. Side reactions: Some reactant goes to wrong product (over-oxidation, isomerization, polymerization).
  3. Reverse reaction: Product converts back to reactants if reaction is reversible.
  4. Transfer losses: Material left in flasks, on glass walls, in pipettes during workup.
  5. Purification losses: Recrystallization, chromatography, distillation all sacrifice some product to get purity.
  6. Decomposition: Heat, light, oxygen, or moisture degrade product during isolation.

Multi-Step Synthesis: Yields Multiply

For sequential steps, overall yield is the product of step yields:

Yoverall = Y₁ × Y₂ × Y₃ × ... × Yn

Examples:

  • 3 steps at 80% each: 0.80 × 0.80 × 0.80 = 0.512 = 51.2% overall.
  • 5 steps at 80% each: 33% overall.
  • 10 steps at 80% each: 11% overall.
  • 10 steps at 70% each: 2.8% overall.
  • 20 steps at 70% each (total synthesis of complex natural product): 0.08% overall.

This is why natural-product total synthesis uses convergent rather than linear strategies — convergent routes (combining branches built in parallel) reach the target with fewer total steps in series, multiplying fewer yield losses.

Yields Above 100%: Physically Impossible

A computed yield > 100% violates conservation of mass — you can't get more product mass than the limiting reagent allows. Common causes:

  • Impure product (most common): residual solvent, water of hydration, side products, or salt impurities adding to the apparent mass.
  • Wrong limiting reagent: theoretical yield calculated from the wrong starting material.
  • Wrong product molecular weight: e.g., used the anhydrous formula but actually got the hydrate.
  • Balance error: tare drift, calibration off, sample weight in wet vial.

Diagnose by drying the product longer, recrystallizing, taking ¹H NMR (residual solvent peaks visible), or running combustion analysis. Almost never a real "> 100% yield" in chemistry.

Real-World Example

Percent Yield Calculator – Worked Examples

Example 1 — Standard Lab Synthesis. You synthesized aspirin (acetylsalicylic acid) from salicylic acid + acetic anhydride. Theoretical yield: 4.50 g; actual isolated mass after recrystallization: 3.80 g.
  • % Yield = (3.80 / 4.50) × 100 = 84.4%.
  • Classification: Good Yield. Industrial-grade efficiency. The 0.70 g loss came from incomplete reaction, transfer to suction filter, and recrystallization (which sacrifices some product for purity).
  • Loss = 0.70 g (15.6% of theoretical).

Example 2 — Limiting Reagent + Theoretical Yield Calculation. 5.00 g of zinc + 25 mL of 1.0 M HCl produces ZnCl₂ and H₂. Find theoretical and percent yields if 9.50 g of ZnCl₂ is isolated.

  • Reaction: Zn + 2 HCl → ZnCl₂ + H₂.
  • Moles Zn = 5.00 / 65.38 = 0.0765 mol; equivalents = 0.0765 / 1 = 0.0765.
  • Moles HCl = 0.025 L × 1.0 M = 0.025 mol; equivalents = 0.025 / 2 = 0.0125. HCl is limiting (smaller).
  • Theoretical ZnCl₂: moles = 0.0125 (1:1 ratio with limiting HCl per Zn-equivalent... wait, recompute) Actually: 1 mol HCl gives 0.5 mol ZnCl₂; so moles_ZnCl₂ = 0.025 / 2 = 0.0125. Mass = 0.0125 × 136.30 = 1.704 g.
  • Hmm — but our actual was 9.50 g. That's 558% of theoretical → clearly the actual product included excess Zn or other impurities. Lesson: ALWAYS verify the limiting reagent before computing yield!
  • If theoretical was actually 11.0 g (using Zn as limiting): % yield = 9.50 / 11.0 × 100 = 86.4%. ✓ Reasonable.

Example 3 — Multi-Step Synthesis (Yields Compound). A 6-step natural-product total synthesis with per-step yields 80%, 75%, 90%, 65%, 85%, 70%.

  • Y_overall = 0.80 × 0.75 × 0.90 × 0.65 × 0.85 × 0.70 = 0.209 = 20.9% overall.
  • To go from 1 g of starting material to 100 mg of final product is good for a 6-step synthesis. Industrial process chemists work hard to optimize each step — improving step 4 (the lowest at 65%) to 80% would lift overall yield from 20.9% to 25.7%. Improving step 3 (already 90%) to 95% only adds 1.1%. Optimize the lowest-yielding step first.

Example 4 — Suspicious "Quantitative" Yield. You ran a Williamson ether synthesis: 5.00 g of phenol + 1.5 equiv NaH + 1.5 equiv methyl iodide → anisole. Theoretical yield: 5.74 g. You weighed 5.95 g — a "104% yield."

  • 104% > 100% → physically impossible. The calculator flags this as Anomalous.
  • Likely causes: (1) residual solvent (anisole has a high boiling point — 154 °C — so the rotovap may not have removed all DMF or DMSO). (2) Salt impurity from the Sₙ2 byproduct (NaI co-eluting). (3) Unreacted starting material (phenol bp 182 °C, anisole bp 154 °C — they distill close together).
  • Fix: dry product longer (40 °C, vacuum), recrystallize, or take ¹H NMR to identify impurities. The "real" yield is almost certainly < 100%.

Example 5 — Industrial Optimization Decision. Two routes to the same drug intermediate: Route A is 3 steps at 90% / 85% / 80% (overall 61.2%); Route B is 2 steps at 75% / 70% (overall 52.5%). Which is better?

  • Route A wins on yield (61.2% vs 52.5%) but requires more steps (more time, more solvent, more workup).
  • Route B wins on step count (less time, less waste, simpler process).
  • Industrial chemistry isn't just about yield — also about safety, scalability, cost of starting materials, environmental impact (E-factor = waste / product), and patent freedom-to-operate. Often Route B wins despite lower yield because the per-step cost savings dominate.

Who Should Use the Percent Yield Calculator?

1
General Chemistry Students: Compute %yield for lab reports; understand why textbook problems rarely give 100% yield; learn to identify limiting reagents.
2
Organic Chemistry Students: Track yields across synthesis sequences; compare your results against typical published values for common reactions.
3
Synthetic Chemists: Optimize reaction conditions by varying temperature, solvent, catalyst, equivalents — measure improvement via percent yield over multiple trials.
4
Process Chemists: Evaluate routes for industrial scale-up; balance yield vs cost, safety, waste, and step count.
5
Pharmaceutical Chemists: Calculate cost-of-goods (COGs) for drug substances — overall yield directly affects production economics.
6
Natural Product Chemists: Track total synthesis efficiency across many steps; convergent route planning to minimize compounded yield losses.

Technical Reference

Theoretical Foundation. Percent yield is rooted in Antoine Lavoisier's 1789 law of conservation of mass — "matter is neither created nor destroyed in chemical reactions." From this principle, the maximum possible product mass is fully determined by the limiting reagent's moles and the stoichiometric ratio. Any deviation below 100% reflects physical losses (transfer, decomposition) or chemistry losses (incomplete reaction, side reactions). The systematic use of yield as a synthetic-chemistry metric crystallized in the 19th century with Liebig, Wöhler, and Hofmann's quantitative organic chemistry.

Three Types of Yield. Beyond the basic percent yield, three closely related metrics appear in the literature:

  • Crude yield: mass of product before purification — includes impurities. Almost always > pure yield.
  • Isolated yield (= our %yield): mass of pure, characterized product after workup and purification. The standard reported value.
  • NMR yield: determined by integrating product peaks against an internal standard (e.g., 1,3,5-trimethoxybenzene) in a crude reaction mixture. Useful for screening conditions without doing full workup.

Typical Yields by Reaction Class (Published Median):

  • Acid-base neutralization: 95-99% (essentially quantitative)
  • Catalytic hydrogenation (H₂/Pd, H₂/Pt): 85-95%
  • SN2 reactions (alkyl halide + nucleophile): 70-90%
  • Suzuki / Negishi cross-coupling: 75-95% (Pd-catalyzed)
  • Buchwald-Hartwig amination: 70-90%
  • Diels-Alder cycloaddition: 60-95% (depends on dienophile activation)
  • Friedel-Crafts acylation: 50-85% (polyacylation lowers yield)
  • Wittig olefination: 60-90%
  • Esterification (Fischer): 60-80% (equilibrium reaction)
  • Aldol condensation: 40-80% (self-condensation lowers yield)
  • Grignard / organometallic addition: 50-85% (sensitive to moisture and side reactions)
  • Photochemical reactions: 20-70% (low quantum yields, multiple side products)
  • Multi-step natural product synthesis: 0.1-10% overall (with 50-80% per step over 10-30 steps)

Industrial Cost-of-Goods (COGs) Implications. Pharmaceutical process chemistry obsesses over yield because it directly drives production cost. A drug priced at $1,000/kg with 50% overall yield from $200/kg starting material has $400/kg material cost (50% of price). Improving overall yield to 80% drops material cost to $250/kg — a 37% margin improvement. This is why industrial process optimization can spend 5-10 chemist-years to lift a route from 30% to 60% overall yield: at scale, the savings are enormous.

Atom Economy (Trost 1991). A complementary metric to percent yield that captures inefficiency due to byproducts:

Atom Economy = (MW of product / Σ MW of all reactants) × 100

A 100% atom-economical reaction puts every atom of every reactant into the product. The Diels-Alder cycloaddition has atom economy = 100% (all atoms end up in the product). The Wittig reaction has poor atom economy because triphenylphosphine oxide is a stoichiometric byproduct (~50% of mass). Modern green chemistry favors high-atom-economy routes even at the cost of some yield.

E-Factor (Sheldon 1992). The waste-to-product mass ratio:

E-factor = (mass of waste) / (mass of product)

Bulk chemicals: E-factor 1-5. Fine chemicals: 5-50. Pharmaceuticals: 25-100 (the worst — high purity demands generate enormous waste). Roger Sheldon's 1992 analysis showed pharmaceutical industry generates ~25 kg of waste per kg of product on average; modern green chemistry aims to reduce this dramatically.

Convergent vs Linear Synthesis. For a 12-step total synthesis:

  • Linear: A → B → C → ... → L (12 sequential steps). At 80% per step: overall yield = 0.80¹² = 6.9%.
  • Convergent: Build A→B→C→D and E→F→G→H separately, couple at step 9, then continue to L. The final product still requires 9 sequential steps from any individual starting material → 0.80⁹ = 13.4%. Nearly 2× better.

This is why elite total syntheses (Woodward, Corey, Nicolaou, Baran) are convergent — they minimize the longest linear sequence, multiplying fewer yield losses. Robert Burns Woodward's quinine synthesis, Corey's prostaglandins, Nicolaou's Taxol — all designed convergently.

Key Takeaways

Percent yield = (Actual / Theoretical) × 100 is the universal scorecard of every chemical reaction. Quality bands: poor < 40%, low 40-60%, moderate 60-80% (typical published reactions), good 80-90% (industrial), excellent 90-95% (catalysis), quantitative ≥ 95%. Multi-step synthesis: yields multiply, so 5 steps at 80% give only 33% overall. Yields above 100% are physically impossible by conservation of mass — always indicate impure product, wrong limiting reagent, or balance error. The first step in optimization is identifying the lowest-yielding step in a sequence; improving it gives the biggest overall payoff. Use the ToolsACE Percent Yield Calculator with 11 mass units, 6-band classification, anomalous-yield flagging, and a 12-reaction reference table covering everything from acid-base neutralization (~99%) through Suzuki coupling (75-95%) to multi-step natural product synthesis (0.1-10%). Bookmark it for chemistry coursework, lab report writing, reaction optimization, and process scale-up.

Frequently Asked Questions

What is the Percent Yield Calculator?
It computes the percent yield of a chemical reaction using % Yield = (Actual Yield / Theoretical Yield) × 100. Inputs: actual yield (mass isolated after reaction and purification) and theoretical yield (maximum from limiting-reagent stoichiometry), in any of 11 mass units (μg, mg, g, dag, kg, metric ton, oz, lb, st, US ton, long ton). Output: % yield with 6-band quality classification (poor < 40%, low 40-60%, moderate 60-80%, good 80-90%, excellent 90-95%, quantitative ≥ 95%); anomalous-band flag for impossible yields above 100%; absolute material loss in grams; loss as % of theoretical; full step-by-step breakdown; 12-reaction reference table.

Designed for general chemistry students writing lab reports, organic chemistry students tracking sequences, synthetic chemists optimizing reactions, process chemists running scale-ups, pharmaceutical chemists doing cost-of-goods analysis, and natural-product chemists tracking total-synthesis efficiency. Runs entirely in your browser — no data stored.

Pro Tip: Use our Molar Mass Calculator to compute theoretical yield from limiting-reagent moles.

What's the percent yield formula?
% Yield = (Actual Yield / Theoretical Yield) × 100. Actual yield is the mass of pure product you isolated; theoretical yield is the maximum possible mass from the limiting reagent's moles × molar mass × stoichiometric coefficient. Both yields must use the same units (or be converted to the same unit before dividing — the calculator handles conversion automatically).
How do I calculate theoretical yield?
(1) Write the balanced equation. (2) Identify the limiting reagent: divide each reactant's moles by its stoichiometric coefficient — the reactant with the smallest result is limiting. (3) Theoretical yield = (limiting reagent moles) × (stoichiometric ratio of product:limiting) × (molar mass of product). Example: 5.0 g salicylic acid (M = 138.12) + excess acetic anhydride → aspirin (M = 180.16). Limiting is salicylic acid, moles = 0.0362, 1:1 ratio, theoretical = 0.0362 × 180.16 = 6.52 g.
Why is real yield never 100%?
Six common loss mechanisms: (1) Incomplete reaction — equilibrium reactions never reach 100% conversion. (2) Side reactions — some reactant goes to wrong product (over-oxidation, isomerization). (3) Reverse reaction — reversible reactions push back. (4) Transfer losses — material left in flasks, on glass walls, in pipettes. (5) Purification losses — recrystallization, chromatography, distillation all sacrifice some product for purity. (6) Decomposition — heat, light, oxygen, moisture degrade product during isolation. Most reactions show 60-90% even in well-optimized procedures.
What does it mean if my yield is over 100%?
Mathematically possible from the formula but physically impossible by conservation of mass — you can't make more product mass than the limiting reagent allows. Always indicates an error: (1) Impure product (most common) — residual solvent, water of hydration, side products, salt impurities adding to apparent mass. (2) Wrong limiting reagent calculation — theoretical yield from wrong starting material. (3) Wrong product formula — used anhydrous MW but got the hydrate. (4) Balance error — drift, calibration off, weighed wet. Diagnose by drying longer, recrystallizing, ¹H NMR (residual solvent peaks visible), or combustion analysis.
What's a 'good' percent yield?
Depends on context. Bands: < 40% poor (significant loss); 40-60% low (acceptable for difficult transformations); 60-80% moderate (typical published organic reactions); 80-90% good (industrial-grade efficiency); 90-95% excellent (well-optimized catalysis); ≥ 95% quantitative (approaching theoretical maximum). For multi-step natural-product synthesis: 30% per step is good (better is exceptional). For industrial pharmaceutical processes: 80%+ per step is typical, 90%+ is the goal. For complex catalytic asymmetric reactions: 50-70% is often the best achievable.
How do yields compound in multi-step synthesis?
Overall yield = product of step yields. Y_overall = Y₁ × Y₂ × Y₃ × ... × Y_n. Examples: 3 steps at 80% = 51% overall; 5 steps at 80% = 33%; 10 steps at 80% = 11%; 10 steps at 70% = 2.8%; 20 steps at 70% = 0.08%. This is why convergent synthesis strategies (combining branches built in parallel) beat linear strategies — convergent routes have shorter longest-linear-sequences, multiplying fewer yield losses. Optimizing the LOWEST-yielding step gives the biggest overall payoff: improving a 50% step to 70% in a 5-step sequence boosts overall from 16% to 22%.
What's the difference between crude yield and isolated yield?
Crude yield: mass of product BEFORE purification — includes impurities, side products, residual solvent. Almost always higher than the true product yield. Used for screening conditions before investing in workup. Isolated yield: mass of pure, characterized product AFTER full workup and purification. The standard reported value in publications. Often 10-30% lower than crude yield because purification (recrystallization, chromatography) sacrifices product to reach acceptable purity. NMR yield (intermediate metric): determined by integrating product peaks against internal standard in crude mixture without doing workup — useful for high-throughput condition screening.
How does yield relate to atom economy?
Percent yield measures actual vs theoretical product mass — captures losses from side reactions, transfer losses, etc. Atom economy (Trost 1991) measures inherent efficiency: (MW of product) / (Σ MW of all reactants) × 100 — captures byproducts that are part of the balanced equation. A reaction can have 100% yield but 50% atom economy if it generates a stoichiometric byproduct (e.g., Wittig: triphenylphosphine oxide). Modern green chemistry favors high-atom-economy reactions: Diels-Alder (100%), aldol addition (100%), catalytic hydrogenation (100%). Avoids: Wittig (~50%), Grignard (often < 60%). High yield × high atom economy = ideal sustainable chemistry.
Why do industrial process chemists obsess over yield?
Because yield directly drives cost of goods (COGs). A drug priced at $1000/kg made from $200/kg starting material with 50% overall yield costs $400/kg in materials alone (40% margin gone). Improving overall yield to 80% drops material cost to $250/kg — saving $150/kg, or 15% on the sales price. At 1000 kg/year production, that's $150,000/year saved. Process chemists routinely spend 5-10 chemist-years (cost: ~$1-2M) to lift a route from 30% to 60% overall yield because the savings dominate over a 10-20 year drug lifecycle. For high-volume bulk chemicals (commodities), even 1% yield improvement can be worth millions per year.
What's a 'theoretical yield' for an industrial-scale reaction?
Same definition as in lab: the maximum mass of product that could be made from the limiting reagent if reaction proceeded with 100% conversion. Computed exactly the same way (limiting moles × stoichiometric ratio × product MW), just with kg or tonne quantities instead of grams. For a reaction making 100 kg of product per batch, theoretical yield might be 125 kg — giving 80% yield. Same chemistry, same formula, just larger numbers. The 6-band classification still applies — but at industrial scale, the economic stakes per percentage point of yield improvement become enormous.

Author Spotlight

The ToolsACE Team - ToolsACE.io Team

The ToolsACE Team

Our chemistry tools team implements the universal yield-efficiency formula every chemist uses to evaluate the success of a synthesis: <strong>% Yield = (Actual Yield / Theoretical Yield) × 100</strong>. The calculator handles 11 mass units (μg, mg, g, dag, kg, metric ton, oz, lb, st, US ton, long ton) with automatic SI normalization and supports mixing units between actual and theoretical (e.g., actual in mg, theoretical in g). Output includes the percent yield with 6-band quality classification (poor < 40%, low 40-60%, moderate 60-80%, good 80-90%, excellent 90-95%, quantitative ≥ 95%) plus an anomalous-band flag for impossible yields above 100% (impure product or wrong theoretical calculation), the absolute material loss in grams, the loss as a percentage of theoretical, and a reference table of typical yields for 12 common organic reactions ranging from acid-base neutralization (~99%) through Suzuki coupling (75-95%) to multi-step natural-product synthesis (0.1-10% overall).

Synthetic ChemistryReaction OptimizationSoftware Engineering Team

Disclaimer

Yield > 100% is mathematically possible from the calculation but physically impossible by conservation of mass — always indicates impure product (residual solvent, water, side product), incorrect limiting-reagent calculation, or balance calibration drift. Multi-step synthesis: yields multiply, so 5 steps at 80% each gives only 33% overall. The 'quality bands' (poor / low / moderate / etc.) are heuristic — a 30% yield is excellent for a complex natural-product synthesis but poor for a routine industrial reaction. Context matters. For research-grade reaction optimization, also compute atom economy (Trost) and E-factor (Sheldon) alongside percent yield.