Percent Yield Calculator

Percent yield compares how much product was actually obtained to how much theory predicts. A 100% yield is ideal but rarely achieved due to side reactions, incomplete reactions, and losses during purification.

📊 Stoichiometry📐 % Yield = (actual/theoretical) × 100⚗️ Reactions

Actual Yield (g)

Theoretical Yield (g)

Please enter valid values.

Formula & Reference

Variable	Symbol	Formula	Units
Percent Yield	% yield	(actual/theoretical) × 100	% (0–100)
Actual Yield	—	Mass of product actually collected	g
Theoretical Yield	—	Max possible from limiting reagent	g
Reverse	Actual	(% yield/100) × theoretical	g

Step-by-Step Examples

Example 1

Aspirin Synthesis

Theoretical yield = 14.40 g. Actual collected = 12.20 g.

% yield = (12.20/14.40) × 100
% yield = 84.7%

✓ 84.7% yield — good for student lab

Example 2

Industrial Process

Reactor theoretical output = 500 kg. Actual = 465 kg.

% yield = (465/500) × 100 = 93.0%

✓ 93.0% industrial yield

Example 3

Find Actual Yield

If % yield = 78% and theoretical = 25.0 g:

actual = (78/100) × 25.0 = 19.5 g

✓ 19.5 g actual yield

Real-World Applications

🏭

Industrial Optimization

Higher yield = lower cost. Improving yield from 85% to 95% in a large plant saves millions.

🧪

Pharmaceutical Synthesis

Drug synthesis may require many steps; each step yield compounds to determine overall yield.

🌍

Green Chemistry

Maximizing atom economy and percent yield reduces waste and environmental impact.

📊

Quality Assessment

Percent yield measures how well a reaction was performed and controlled.

Common Mistakes to Avoid

⚠️

Actual yield greater than theoretical

If your actual > theoretical, recheck. This is impossible. Possible causes: impure product, calculation error, or wrong theoretical.

⚠️

Wrong theoretical yield

Theoretical yield must be calculated from the LIMITING reagent. Using excess reagent gives a wrong (too high) theoretical.

⚠️

Including impurities in actual yield

Actual yield is the mass of PURE product. If your product contains moisture or byproducts, the yield is artificially inflated.

Frequently Asked Questions

Why is 100% yield almost never achieved? ▾

Side reactions, equilibrium limitations, incomplete reactions, transfer losses, and purification steps all reduce actual yield.

What is a good percent yield? ▾

Depends on the reaction. Industrial: typically 85-95%. Multi-step synthesis: each step at 90% gives (0.9)^10 = 35% overall for 10 steps.

What is atom economy vs percent yield? ▾

Atom economy = (desired product MW / sum of all reactant MW) × 100. Measures efficiency of atoms used. Different from percent yield which measures reaction completion.

How do I improve percent yield? ▾

Optimize temperature, pressure, concentration, time. Use catalysts. Minimize handling losses. Remove products as formed (Le Châtelier).

What is theoretical yield based on? ▾

Theoretical yield is calculated from the limiting reagent using stoichiometry. It assumes 100% of limiting reagent converts to product.

Related Chemistry Calculators

Formula Explorer connections

Interpretation: This relationship converts chemical amount, mass, composition or balanced-equation ratios into a reaction quantity. Assumption: Use a balanced reaction, consistent units and the correct molar mass. Purity, side reactions and limiting reagents can change experimental results.

Percent Yield Calculator →Reaction Yield Calculator →Stoichiometry Calculator →Chemistry Formula Explorer →