Reactions & Stoichiometry

Stoichiometry Calculator

Balance a reaction and calculate limiting reactants, excess amounts, and maximum product.

1

Enter values

Comma-separated formula=value unit pairs for every reactant.
Examples
2

Results

Ready to calculate

Your result, units, method, and version information will appear here.

How to use this calculator

  1. Enter the chemical equation and one quantity for each reactant.
  2. Use the formula, value, and unit format shown below the field.
  3. Enter the desired product formula.
  4. Calculate and review the balanced equation, limiting reactant, and excess amounts.

Formula and variables

reaction extent = nᵢ / nuᵢ

SymbolMeaningUnit
nᵢspecies amountmol
nuᵢbalanced coefficientdimensionless

Worked example

For 2 H2 + O2 -> 2 H2O, H2=4 mol and O2=1 mol makes O2 limiting and permits 2 mol H2O.

Interpretation

The smallest available stoichiometric extent identifies the limiting reactant; remaining material is computed from that same extent.

Common mistakes

  • Supply one quantity for every reactant using the displayed formula labels.
  • Mass quantities require atomic data for every element in the formula.

Frequently asked questions

Can I mix grams and moles in one calculation?

Yes. The calculator converts each reactant quantity to moles before it compares reaction extents.

Does the calculator balance the equation first?

Yes. It uses exact integer coefficients before it applies any quantity ratio.

What does maximum product mean?

It is the theoretical product amount from the available reactants under complete conversion.

Can I use scientific notation?

Yes. Enter values such as 6.022e23 or 1.0e-6 in a numeric field.

How should I round the result?

Keep extra digits during the calculation. Round the final result to the precision required by your data.

Sources