Stoichiometry Calculator

Our Stoichiometry Calculator uses mole ratios from a balanced chemical equation to find the theoretical yield of any substance. Here's how:

Step 1: Write or look up your balanced chemical equation. The coefficients in front of each substance are the mole ratios you need.

Step 2: Enter the known moles (n₁) of the substance you are starting with.

Step 3: Enter the equation coefficient of that known substance (c₁) and the coefficient of the target substance (c₂).

Step 4: Click 'Calculate Target Moles' to find n₂ — the theoretical moles of your target substance.

Note: This calculator assumes 100% theoretical yield. In real reactions, actual yield will be lower due to limiting reactants, side reactions, and losses.

Stoichiometry is built on the mole ratio derived from a balanced equation:

n₂ = n₁ × (c₂ / c₁)

Where: - n₁ = moles of the known substance (given) - n₂ = moles of the target substance (calculated) - c₁ = stoichiometric coefficient of the known substance - c₂ = stoichiometric coefficient of the target substance

This works because a balanced equation guarantees that c₁ moles of substance 1 always react with or produce c₂ moles of substance 2. The ratio c₂/c₁ is the mole ratio, and multiplying n₁ by this ratio scales the known quantity up or down to find n₂.

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. The word comes from the Greek words for 'element' and 'measure', and it is exactly that — a precise measurement framework that tells you how much of each substance participates in or results from a reaction.

At the heart of stoichiometry is the balanced chemical equation. A balanced equation obeys the law of conservation of mass: the number of atoms of each element is identical on both sides of the equation. The numbers in front of each compound — the stoichiometric coefficients — represent the exact mole ratios in which substances react and are produced. For example, in 2H₂ + O₂ → 2H₂O, two moles of hydrogen react with one mole of oxygen to produce two moles of water.

The mole is the central unit in stoichiometry. One mole of any substance contains approximately 6.022 × 10²³ particles (Avogadro's number). Using moles allows chemists to scale from individual atoms — too small to weigh — to measurable laboratory quantities. Converting between grams and moles using molar mass is a routine first step before applying the mole ratio.

Stoichiometry underpins nearly all quantitative work in chemistry: pharmaceutical manufacturing uses it to calculate drug yields; industrial chemical plants rely on it to optimize reactions and minimize waste; and environmental scientists use it to model combustion emissions and pollution budgets. Even when you follow a recipe that doubles all ingredient quantities, you're applying the same principle of proportional scaling.