Percent Yield Calculator Formula
Understand the math behind the percent yield calculator. Each variable explained with a worked example.
Formulas Used
Percent Yield
pct_yield = (actual_yield / theoretical_yield) * 100Product Lost
loss = theoretical_yield - actual_yieldVariables
| Variable | Description | Default |
|---|---|---|
actual_yield | Actual Yield(g) | 3.5 |
theoretical_yield | Theoretical Yield(g) | 5 |
How It Works
Percent Yield
Percent yield measures how efficient a chemical reaction is by comparing the actual product obtained to the maximum amount theoretically possible.
Formula
% Yield = (Actual Yield / Theoretical Yield) × 100
Theoretical yield is calculated from stoichiometry using the limiting reagent. Percent yields below 100% are caused by incomplete reactions, side reactions, and losses during purification.
Worked Example
A synthesis produces 3.5 g of product from a theoretical maximum of 5.0 g.
- 01% Yield = (3.5 / 5.0) × 100 = 70.00%
- 02Product lost = 5.0 - 3.5 = 1.5 g
Frequently Asked Questions
Can percent yield exceed 100%?
In theory, no. A yield above 100% usually means the product is impure (contains solvent, byproducts, or unreacted starting material) or there is a measurement error.
What is a good percent yield?
It depends on the reaction. Simple reactions may give 90%+ yield. Multi-step organic syntheses often give 50-80% per step. Transition metal-catalyzed reactions can vary widely from 30-95%.
How do I find the theoretical yield?
Identify the limiting reagent using stoichiometry, then calculate the maximum moles of product from the limiting reagent. Multiply by the product molecular weight to get grams.
Ready to run the numbers?
Open Percent Yield Calculator