What is theoretical yield?

Theoretical yield is the maximum mass of product that could be produced in a reaction if the limiting reagent is completely consumed with 100% efficiency, based solely on stoichiometry.

How do I find the limiting reagent?

Divide the moles of each reactant by its stoichiometric coefficient. The reactant with the smallest resulting value is the limiting reagent. Enter that value in the Moles of Limiting Reagent field.

What is percent yield and why is it less than 100%?

Percent yield = (actual yield / theoretical yield) × 100. Real reactions rarely reach 100% due to side reactions, incomplete reactions, losses during purification, or measurement errors.

What stoichiometric ratio should I use?

Use the coefficients from the balanced chemical equation. For example, in N₂ + 3H₂ → 2NH₃, producing NH₃ from H₂ gives a ratio of 2 product : 3 reactant, so enter 2 for product and 3 for reactant.

What units does this calculator use?

Molar masses are in grams per mole (g/mol), limiting reagent quantity in moles (mol), and the resulting theoretical yield in grams (g). Percent yield is dimensionless (%).

Theoretical Yield Calculator

Calculate the maximum amount of product obtainable from a chemical reaction given the limiting reagent, molar masses, and stoichiometric coefficients.

Reaction Inputs

Moles of Limiting Reagent (mol)

Molar Mass of Limiting Reagent (g/mol, optional reference)

Molar Mass of Product (g/mol)

Stoichiometric Coefficients (from balanced equation)

Reagent coefficient

Product coefficient

Example: N₂ + 3H₂ → 2NH₃ → reagent=3, product=2

Actual (Experimental) Yield — optional (g)

Fill in the inputs and click Calculate to see results.

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Summary

This theoretical yield calculator determines the maximum mass of product that can be formed in a chemical reaction. Enter the moles of your limiting reagent, its molar mass, the product molar mass, and the stoichiometric ratio to instantly compute the theoretical yield in grams. It also calculates percent yield when you provide an actual yield.

How it works

Enter the moles of the limiting reagent you have.
Input the molar mass of the limiting reagent (g/mol).
Input the molar mass of the desired product (g/mol).
Set the stoichiometric coefficients from the balanced equation.
Click Calculate to see the theoretical yield in grams and moles.
Optionally enter your actual (experimental) yield to get percent yield.

Use cases

Plan lab-scale synthesis reactions to estimate how much product to expect.
Verify stoichiometric calculations for chemistry homework and exams.
Determine limiting reagent impact on reaction efficiency.
Calculate percent yield when comparing experimental to theoretical results.
Scale reactions up or down by adjusting moles of limiting reagent.
Cross-check mole-to-gram conversions in multi-step organic synthesis.

Frequently Asked Questions

Last updated: 2026-06-04 · Reviewed by Nham Vu