Percent Yield Calculator
What This Calculator Does
This percent yield calculator determines the efficiency of a chemical reaction by comparing the actual amount of product obtained to the maximum theoretical amount possible. Percent yield is a key metric in chemistry for evaluating reaction performance and optimization.
Percent Yield Formula
Primary Formula
% Yield
Percent (%)
Actual
Obtained (g, mol)
Theoretical
Calculated (g, mol)
Actual = (% Yield × Theoretical) / 100
Calculate actual yield from percent
Theoretical = (Actual × 100) / % Yield
Calculate theoretical yield from percent
Step-by-Step Example
Problem: A reaction should theoretically produce 50.0 g of product, but only 42.5 g was actually obtained. Calculate the percent yield.
- 1Identify the values: Actual = 42.5 g, Theoretical = 50.0 g
- 2Apply the formula: % Yield = (42.5 / 50.0) × 100
- 3Calculate: % Yield = 0.85 × 100 = 85%
- 4Result: The reaction achieved 85% yield (good efficiency)
Common Mistakes to Avoid
Reversing Actual and Theoretical
Always divide actual by theoretical, not the reverse
Using Inconsistent Units
Both yields must use the same units (grams or moles)
Forgetting to Multiply by 100
The result must be multiplied by 100 to get percentage
Incorrect Theoretical Calculation
Theoretical yield must be calculated from stoichiometry and limiting reagent
Where Percent Yield Is Used
Education
Essential concept in chemistry courses for evaluating reaction efficiency and laboratory technique
Laboratory
Standard metric for assessing synthesis experiments and reaction optimization
Industry
Critical for pharmaceutical manufacturing, chemical production, and process cost analysis
Research
Quantifying reaction performance in synthetic chemistry and method development
Related Calculators
Limiting Reagent Calculator
Determine which reactant limits product formation
Theoretical Yield Calculator
Calculate maximum possible product from stoichiometry
Empirical Formula Calculator
Determine empirical formula from percent composition
Related Formulas
Frequently Asked Questions
What is percent yield in chemistry?
Percent yield measures reaction efficiency by comparing actual product obtained to the maximum theoretical amount possible. It's expressed as a percentage, with 100% being a perfect reaction.
Can percent yield exceed 100%?
No, percent yield should never exceed 100%. If it does, there's an error—likely impurities in the product, incomplete drying, incorrect theoretical calculation, or measurement mistakes.
What is a good percent yield?
In research labs, 70-90% is considered good, and above 90% is excellent. Industrial processes aim for higher yields (>95%) for economic reasons. Yields vary depending on reaction complexity.
Why is percent yield less than 100%?
Common reasons include incomplete reactions, side reactions, product loss during purification, measurement errors, and reversible equilibrium reactions that don't go to completion.
How do you calculate theoretical yield?
Use stoichiometry: identify the limiting reagent, use mole ratios from the balanced equation to find moles of product, then convert to grams using molar mass. This is your theoretical yield.
Does temperature affect percent yield?
Yes indirectly. Temperature doesn't change the theoretical yield calculation, but it affects reaction rate, equilibrium position, and side reactions—all of which impact actual yield and thus percent yield.
What units are used for percent yield?
Percent yield is unitless (expressed as %). Both actual and theoretical yields must use the same units (grams, moles, or any consistent unit) before calculating the percentage.
How can you improve percent yield?
Optimize reaction conditions (temperature, pressure, catalyst), minimize side reactions, improve purification techniques, ensure complete mixing, use excess of cheaper reagents, and reduce product loss during transfers.
Reviewed for accuracy by Muhammad Zohaib, MSc Chemistry
All formulas verified against academic standards • Editorial Policy