Theoretical Yield Calculator
Find the limiting reactant and theoretical yield from the masses and coefficients of up to two reactants, with excess left and percent yield.
Minimum: 0
Mass of the first reactant. With the reactant B fields blank, A is treated as the limiting reactant.
Must be greater than 0
Minimum: 0
Optional. Fill in all three reactant B fields to find which reactant limits.
Must be greater than 0
Must be greater than 0
A's coefficient in the balanced equation (1 for N₂ in N₂ + 3H₂ → 2NH₃).
Must be greater than 0
B's coefficient in the balanced equation (3 for H₂ in N₂ + 3H₂ → 2NH₃).
Must be greater than 0
The product's coefficient in the balanced equation (2 for NH₃ in N₂ + 3H₂ → 2NH₃).
Must be greater than 0
Minimum: 0
Optional. The mass of product you collected, for the percent yield.
Results
Limiting Reactant
Reactant A
Reactant A Moles
0.1667 mol
Product Moles
0.1667 mol
Theoretical Yield
30 g
Note
Reactant B is blank, so reactant A is treated as the limiting reactant.
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Theoretical Yield Calculator. Follow the units and input format printed next to each field. Where a unit selector is available, choose the units that match your data.
Review your inputs
Double-check that all values are correct and match the units or format shown for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The Theoretical Yield Calculator computes the output in your browser and displays the results, with units clearly labeled, as soon as they are ready — no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
When to Use This Calculator
- •Use the Theoretical Yield Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
- •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
- •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
- •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.
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About Theoretical Yield Calculator
The theoretical yield calculator predicts the maximum mass of product a reaction can form, assuming it goes to completion with no losses. Enter reactant A's mass, molar mass and coefficient from the balanced equation, then the product's coefficient and molar mass. To find the limiting reactant, also fill in a second reactant B: the calculator divides each reactant's moles by its coefficient, takes the smaller result as the limiting reactant (or reports a tie), and gives the product moles, the theoretical yield in grams and how much of the excess reactant is left. With reactant B blank, reactant A is treated as the limiting reactant. Enter the mass of product you actually collected to get the percent yield as well. The calculator compares at most two reactants and assumes one balanced reaction with no side reactions.
The Math Behind It
Formula Reference
Moles and Reaction Extent
n = m / M; ξ = n / coefficient
Variables: m = reactant mass (g); M = molar mass (g/mol); n = moles; ξ = how many times the balanced reaction can run on that reactant
Limiting Reactant
ξ = min(n_A / a, n_B / b)
Variables: a, b = coefficients of reactants A and B in the balanced equation; the reactant with the smaller n / coefficient limits; with reactant B blank, ξ = n_A / a
Theoretical Yield
Yield = p × ξ × M_P
Variables: p = product coefficient; ξ = the reaction extent the limiting reactant allows; M_P = product molar mass (g/mol)
Excess Reactant Left
n_left = n_excess − coefficient_excess × ξ
Variables: n_excess = moles of the reactant in excess; mass left = n_left × its molar mass
Percent Yield
% yield = actual / theoretical × 100
Variables: actual = mass of product collected (g); theoretical = theoretical yield (g)
Worked Examples
Example 1: Synthesis from acetic acid
10 g of acetic acid (MW 60) reacts to form a product (MW 180) with a 1:1 mole ratio (both coefficients 1), with no second reactant entered.
The maximum product obtainable is 30.0 g.
Example 2: Limiting reactant in ammonia synthesis
28.0 g of N₂ (28.014 g/mol) reacts with 10.0 g of H₂ (2.016 g/mol) in N₂ + 3H₂ → 2NH₃ (NH₃ 17.031 g/mol), and 30.0 g of NH₃ is collected.
N₂ limits: the theoretical yield is 34.045 g of NH₃, 3.955 g of H₂ is left over, and the percent yield is 88.12%.
Common Mistakes & Tips
- !Not balancing the equation, leading to the wrong coefficients.
- !Comparing reactant masses, or moles without dividing by the coefficients, to pick the limiting reactant.
- !Forgetting to convert grams to moles before applying the coefficients.
- !Entering a product-to-reactant mole ratio as the product coefficient when reactant A's coefficient isn't 1: enter both coefficients as they appear in the balanced equation.
Related Concepts
Used in These Calculators
Calculators that build on or apply the concepts from this page:
Frequently Asked Questions
How do I identify the limiting reactant?
Convert each reactant mass to moles, divide by its coefficient in the balanced equation, and compare. The reactant that gives the smallest quotient is the limiting reactant. Fill in reactant B and this calculator makes that comparison for two reactants.
What if my reaction has three or more reactants?
The calculator compares two reactants at a time. Enter two of them and note which one limits, then compare that reactant with the next one: the reactant that limits in every comparison limits overall, and the last comparison gives the theoretical yield. The excess shown is only for the other reactant in that comparison.
Does theoretical yield account for equilibrium?
No. Theoretical yield assumes the reaction goes to 100% completion. For reversible reactions, the actual yield will be less due to equilibrium limitations.
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