Theoretical Yield Calculator

How to use the theoretical yield calculator

What this calculator does

This calculator estimates the maximum mass of a desired product that can form from a known amount of a limiting reagent. It converts reagent mass to moles, corrects for the coefficient of that reagent in a balanced chemical equation, applies the product coefficient, and converts the resulting product moles back to mass. The result is an ideal upper bound. It does not predict losses from incomplete conversion, equilibrium, side reactions, transfer losses, purification, or measurement uncertainty.

When to use it

Use it before a laboratory synthesis to estimate the most product that could be obtained, when checking a hand-written stoichiometry calculation, when planning reagent quantities, or when preparing a denominator for a later percent-yield calculation. The calculation is appropriate only after the chemical equation is balanced and the limiting reagent has been identified.

How to calculate

1. The calculator opens with a complete demonstration: 2 g of a limiting reagent with molar mass 26 g/mol and coefficient 1 produces a product with coefficient 1 and molar mass 85 g/mol. The result and a validated Excel workbook are immediately available.
2. Replace each demonstration value with data from your own balanced reaction. Choose mg, g, or kg beside Limiting reagent mass; the calculator converts that mass to grams internally while returning the theoretical yield in the selected mass unit.
3. Read Theoretical yield first, then use Limiting reagent moles, Reaction extent, Desired product moles, and the calculation trail to verify each transformation.
4. Select Download Excel to export the current typed inputs and canonical results. Select Reset to clear the demonstration and all calculated content; export remains unavailable until every required field again contains a valid positive value.

Input guide

Limiting reagent mass is required and accepts a positive decimal number using a period as the decimal separator, such as 2, together with the adjacent Mass unit control. Changing mg, g, or kg converts the current displayed value rather than merely relabeling it. Do not enter a unit symbol in the text box or use a decimal comma. A larger limiting-reagent mass increases product yield proportionally when all other values stay fixed.

Limiting reagent molar mass is required in g/mol; enter a positive value such as 26. It is the molar mass of the reactant already identified as limiting. A higher molar mass means fewer moles are present in the same mass, so the predicted yield decreases. A common mistake is entering an atomic mass for only part of a compound.

Limiting reagent coefficient and Desired product coefficient are required positive stoichiometric numbers from the balanced equation, commonly integers such as 1 or 2, though exact fractional coefficients are mathematically supported. Increasing the limiting-reagent coefficient lowers the reaction extent; increasing the product coefficient raises product moles. Do not use subscripts from a chemical formula in place of equation coefficients. The balanced-equation role of coefficients is explained in the Chemistry LibreTexts guide to balancing equations.

Desired product molar mass is required in g/mol; enter a positive value such as 85. It converts calculated product moles into mass. For the same number of product moles, a larger molar mass gives a larger product mass. Use the complete formula mass of the isolated product and be consistent about hydrates, salts, or solvates.

Output guide

Theoretical yield is the ideal maximum product mass in the selected mass unit. It is an estimate based on exact stoichiometric identity plus the idealized assumption of complete conversion. Limiting reagent moles reports mass divided by molar mass. Reaction extent divides those moles by the limiting-reagent coefficient and represents how many stoichiometric reaction units can occur. Desired product moles multiplies reaction extent by the product coefficient. Stoichiometric ratio is product coefficient divided by limiting-reagent coefficient. Zero is not accepted for any required quantity because it would not describe a meaningful production calculation.

The three summary pills repeat the limiting-reagent moles, product moles, and active mass unit. The Calculation trail table lists the four transformations in order: mass-to-moles, coefficient normalization, product-coefficient scaling, and moles-to-mass. These are exact algebraic identities for the entered model, while the usefulness of the final yield depends on the chemical assumptions.

Worked example

With the startup values, the limiting reagent contains 2 g ÷ 26 g/mol = 0.076923 mol. Dividing by its coefficient of 1 gives a reaction extent of 0.076923 mol reaction. Multiplying by the desired product coefficient of 1 gives 0.076923 mol of product. Finally, 0.076923 mol × 85 g/mol = 6.538 g, matching the first-open theoretical yield. The IUPAC Gold Book definition of stoichiometric number provides authoritative terminology for the coefficients used in this relationship.