Reaction Yield Calculator – Calculate Theoretical and Percent Yield
Calculate the theoretical yield, actual yield, and percent yield of any chemical reaction with our free yield calculator. Understand your reaction efficiency and optimize lab results. Ideal for chemistry students and researchers.
Reaction yield measures how much product you actually obtain compared to the maximum possible amount. The theoretical yield is the maximum product possible based on stoichiometry. The actual yield is what you collect in the lab.
Percent Yield Formula
Why Percent Yield is Less Than 100%
- Incomplete reactions - not all reactants convert to products
- Side reactions - reactants form unwanted byproducts
- Product loss during purification or transfer
- Impure reactants
- Reversible reactions reaching equilibrium
Finding Theoretical Yield
- Balance the chemical equation
- Identify the limiting reagent
- Calculate moles of limiting reagent
- Use stoichiometry to find moles of product
- Convert moles to grams using molar mass
Example Calculation
The theoretical yield of aspirin is 10.0 g. You actually obtain 8.5 g.
Percent Yield = (8.5 g / 10.0 g) × 100% = 85%
Enter values and calculate to see the chart
| Percent Yield | Quality | Assessment |
|---|---|---|
| 90-100% | Excellent | Very efficient reaction |
| 70-89% | Good | Acceptable for most purposes |
| 50-69% | Fair | Room for optimization |
| <50% | Poor | Needs improvement |
Choose Your Calculation Mode
Select whether you want to calculate percent yield, theoretical yield, or actual yield based on your known values.
Enter Your Values
Input the relevant measurements such as actual yield, theoretical yield, moles of limiting reagent, or product molar mass.
Get Instant Results
View your calculated yield with a visual comparison chart and quality assessment guide.
✓Multiple Calculation Modes
Calculate percent yield, theoretical yield, or actual yield depending on what values you have available.
✓Visual Yield Comparison
Interactive bar chart shows the relationship between theoretical and actual yield for easy understanding.
✓Quality Assessment Guide
Reference table helps you interpret your percent yield and understand reaction efficiency.
✓Limiting Reagent Support
Calculate theoretical yield from moles of limiting reagent and product molar mass.
✓Educational Examples
Clear explanations of yield formulas, common loss factors, and step-by-step calculation methods.
What is the formula for percent yield?
Percent yield = (Actual Yield / Theoretical Yield) × 100%. This tells you how efficient your reaction was compared to the maximum possible product.
Why is my percent yield over 100%?
Yields over 100% usually indicate impure product, incomplete drying, or measurement errors. The product may contain solvent, unreacted starting material, or side products adding extra mass.
How do you find the limiting reagent?
Convert all reactant masses to moles, divide by their stoichiometric coefficients from the balanced equation, and identify the reactant with the smallest value. That is your limiting reagent.
What causes low percent yield in reactions?
Common causes include incomplete reactions, side reactions forming byproducts, product loss during filtration or transfer, impure reactants, and reversible reactions reaching equilibrium before completion.
Is 50% yield considered good?
A 50% yield is considered fair. For simple reactions, you should aim for 70% or higher. Complex multi-step syntheses often have lower yields. Context matters - some reactions are inherently low-yielding.
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