Stoichiometry Calculator

The reaction to work from. It does not need to be balanced — the tool balances it first, then uses the coefficients as the mole ratio.

Join species with + and the sides with = or ->.

The one substance whose amount you already know. Every other amount is scaled from it using the balanced mole ratio.

It must match a formula in the equation exactly, e.g. N2.

How much of the known species you have, in the unit chosen below.

Example: 28 g of N2 is one mole, which reacts with 3 mol of H2.

Whether the known amount above is a mass or a number of moles.

• grams: a weighed mass, converted to moles with the molar mass.
• moles: already an amount in moles.