Stoichiometry Calculator
Grams to moles to moles to grams, through the mole ratio.
Work out Stoichiometry. Grams to moles to moles to grams, through the mole ratio. Free, with no account and nothing to download.
From the BALANCED equation. Unbalanced coefficients give a wrong ratio.
Mass of the target substance
36.03 g
2 mol → 2 mol, through 2 : 2
Every stoichiometry problem is this one path: grams to moles by dividing by molar mass, moles to moles through the balanced coefficients, then moles back to grams. Nothing else is happening, however many steps a question wraps around it. The coefficients must come from a balanced equation. Using the unbalanced ones is the single commonest error, and it produces an answer that is wrong by a clean factor — often a whole number, which makes it look deliberate. This assumes complete reaction with the known substance limiting. If both reactant amounts are given, work out the limiting reagent first, because the excess one cannot be used as the starting point.
How the Stoichiometry Calculator works
Enter the mass of what you have, the two coefficients from the balanced equation, and the molar masses, and this returns the mass of what you get. Every stoichiometry problem reduces to this one path however many steps a question wraps around it.
Also known as: mole ratio calculator · mass to mass stoichiometry calculator · gram to gram conversion chemistry · how to do stoichiometry
Frequently asked questions
How do I do a stoichiometry calculation?
Convert grams to moles by dividing by molar mass, convert moles to moles using the coefficients from the balanced equation, then convert back to grams by multiplying by the target's molar mass.
Where do the coefficients come from?
The balanced equation, and only the balanced equation. Using unbalanced coefficients is the commonest error here, and it gives an answer wrong by a clean factor that looks deliberate rather than mistaken.
What if I am given both reactant amounts?
Then find the limiting reagent first. Only the limiting reagent can be used as the starting point — the one in excess is left over and calculating from it overstates the yield.
Does this account for percent yield?
No, this gives the theoretical yield assuming complete reaction. Multiply by your percent yield to get the actual expected mass.
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