# Theoretical Yield Calculator

Calculate theoretical yield from reactant mass, molar masses, and stoichiometric coefficients. Step-by-step solution with mole conversions.

## What this calculates

Figure out the maximum amount of product a chemical reaction can produce. Enter the mass of your limiting reagent, both molar masses, and the balanced equation coefficients to get the theoretical yield in grams.

## Inputs

- **Reactant Mass** (g) — min 0 — Mass of the limiting reagent in grams.
- **Reactant Molar Mass** (g/mol) — min 0.001 — Molar mass of the limiting reagent.
- **Product Molar Mass** (g/mol) — min 0.001 — Molar mass of the desired product.
- **Reactant Coefficient** — min 1, max 20 — Stoichiometric coefficient of the reactant in the balanced equation.
- **Product Coefficient** — min 1, max 20 — Stoichiometric coefficient of the product in the balanced equation.

## Outputs

- **Moles of Reactant** (mol) — Moles of the limiting reagent.
- **Moles of Product** (mol) — Moles of product from the mole ratio.
- **Theoretical Yield** (g) — Maximum mass of product obtainable.
- **Calculation Steps** — formatted as text — Step-by-step calculation.

## Details

Theoretical yield is the maximum mass of product you can get from a reaction, assuming every molecule of the limiting reagent converts perfectly into product. Real reactions rarely hit this number because of side reactions, incomplete conversions, and transfer losses, but it sets the upper bound.

**The Three-Step Process**

1. Convert the reactant mass to moles: divide grams by molar mass
2. Apply the mole ratio from the balanced equation
3. Convert product moles back to grams

**Worked Example**

Suppose you react 10 g of NaOH (molar mass 40 g/mol) with excess HCl. The balanced equation is NaOH + HCl -> NaCl + H2O, so the mole ratio is 1:1.

- Moles of NaOH = 10 / 40 = 0.25 mol
- Moles of NaCl = 0.25 mol (1:1 ratio)
- Theoretical yield = 0.25 x 58.44 = 14.61 g of NaCl

If the ratio were 2:1 (two moles of reactant per mole of product), you would halve the product moles before converting to grams.

**Why It Matters**

You need the theoretical yield to calculate percent yield, which tells you how efficient your reaction actually was. A percent yield of 85% on a 14.61 g theoretical yield means you collected about 12.42 g of product.

## Frequently Asked Questions

**Q: What is theoretical yield?**

A: Theoretical yield is the maximum amount of product a reaction can produce, calculated from stoichiometry. It assumes 100% conversion of the limiting reagent with no side reactions or losses.

**Q: How is theoretical yield different from actual yield?**

A: Theoretical yield is calculated from the balanced equation and reactant amounts. Actual yield is what you physically collect after running the experiment. Actual yield is almost always lower because of side reactions, incomplete conversion, and purification losses.

**Q: Do I need to know the limiting reagent first?**

A: Yes. Theoretical yield is based on the limiting reagent, the reactant that runs out first. If you are unsure which reactant is limiting, use a limiting reagent calculator to compare mole-to-coefficient ratios for each reactant.

**Q: Can theoretical yield be in units other than grams?**

A: The calculation works the same way regardless of mass units. Just make sure the molar mass units match. If you use grams and g/mol, the yield comes out in grams. For milligrams, use mg and mg/mmol (numerically the same as g/mol).

---

Source: https://vastcalc.com/calculators/chemistry/theoretical-yield
Category: Chemistry
Last updated: 2026-04-08