Theoretical Yield Calculator
Theoretical yield is the maximum mass of product that stoichiometry predicts you can obtain from a chemical reaction when the limiting reagent is completely consumed. It represents the upper bound of what you can produce, and your actual yield as a fraction of it gives you the percent yield. Calculating it requires three pieces of information from the balanced chemical equation: the mass and molar mass of the limiting reagent (to find moles), the mole ratio (the number of moles of product produced per mole of limiting reagent, taken from the coefficients in the balanced equation), and the molar mass of the product (to convert moles to grams). The calculation is a straightforward three-step process: divide the reagent mass by its molar mass to get moles; multiply by the mole ratio to get moles of product; multiply by the molar mass of the product to get the mass. This calculator carries out all three steps when you enter the four required values. You can enter the number of moles of limiting reagent directly if you have already converted from mass. The mole ratio field accepts any decimal, so a ratio of 2:3 would be entered as 0.667. The calculator is used in chemistry courses at secondary and university level, in research and industrial settings where accurate yield prediction affects scale-up decisions, and in cost estimation for chemical production.
The mole ratio comes from the balanced chemical equation: moles of product coefficient divided by moles of limiting reagent coefficient. For a 1:1 ratio enter 1.
How it works
Step 1: moles of limiting reagent = mass / molar mass of reagent. Step 2: moles of product = moles of reagent x mole ratio. Step 3: theoretical yield (g) = moles of product x molar mass of product. Written as a single formula: theoretical yield = (mass_LR / MM_LR) x ratio x MM_product.
Worked example
You have 1 g of hydrogen (H2, molar mass 2 g/mol) reacting with oxygen to form water (H2O, molar mass 18 g/mol). The mole ratio is 1:1. Moles of H2 = 1 divided by 2 = 0.5000 mol. Moles of product = 0.5000 x 1 = 0.5000 mol. Theoretical yield = 0.5000 x 18 = 9.00 g. These match the default values pre-filled above.
Related calculators
- Percent Yield Calculator: compare actual yield to theoretical yield as a percentage.
- Stoichiometry Calculator: convert between reactant and product masses for a given equation.
- Molar Mass Calculator: find the molar mass of a reagent or product from its chemical formula.
- Percent Error Calculator: express the deviation of actual yield from theoretical as a percentage error.