Theoretical Yield Calculator

Understanding theoretical yield

Theoretical yield represents the best-case scenario: if every molecule of your limiting reagent reacted perfectly, no product was lost during workup, and no side reactions occurred, this is how much product you’d get. It’s the ceiling against which real experimental results are measured.

The calculation chain is: mass → moles (of reactant) → moles (of product, via stoichiometry) → mass (of product). Each step uses either molar mass or the balanced equation’s mole ratio.

Common mistakes: using the wrong mole ratio (check the balanced equation!), forgetting to identify the limiting reagent in multi-reactant problems, or confusing reactant and product molar masses.

How to Calculate Theoretical Yield (step by step)

Step One: Convert reactant mass to moles

moles of reactant = mass (g) ÷ molar mass of reactant (g/mol)

For 10 g with molar mass 40 g/mol: 10 ÷ 40 = 0.25 mol.

Step Two: Apply the mole ratio

moles of product = moles of reactant × (product coefficient ÷ reactant coefficient)

For a 1:1 ratio: 0.25 × 1 = 0.25 mol product.

Step Three: Convert product moles to grams

theoretical yield = moles of product × molar mass of product (g/mol)

For 0.25 mol with product molar mass 100 g/mol: 0.25 × 100 = 25.0 g.

About the formula: Theoretical Yield = (Mass of reactant ÷ Molar mass of reactant) × Mole ratio × Molar mass of product.

Frequently Asked Questions

What is theoretical yield?+

Theoretical yield is the maximum amount of product that could be formed from a given amount of limiting reagent, assuming 100% conversion and no losses. Real yields are always lower.

How do I find the limiting reagent?+

Calculate the moles of each reactant and divide by their stoichiometric coefficients. The reactant with the smallest result is the limiting reagent — it runs out first and determines the maximum product.

What is the mole ratio?+

The mole ratio comes from the balanced equation. If 2 moles of reactant A produce 1 mole of product B, the product:reactant ratio is 1:2 = 0.5. If it's 1:1, the ratio is 1.

What's the difference between theoretical and actual yield?+

Theoretical yield assumes perfection. Actual yield is what you really collect. Percent yield = (actual/theoretical) × 100 tells you how efficient your reaction was.