Stoichiometry Calculator
Convert between reactant and product masses using balanced equation coefficients.
About Stoichiometry Calculator
Stoichiometry always goes mass to moles, across by the coefficient ratio, then moles back to mass. Attempting to convert mass directly is wrong because mass ratios are not the reaction ratios. The coefficient ratio is the whole content of a balanced equation, and getting it wrong invalidates every downstream figure.
Formula
Stoichiometry
moles reactant → × (coefficient ratio) → moles product → × molar mass
- coefficient ratio
- Ratio of balanced-equation coefficients, the only correct mole conversion
Worked example
With the default values below, Stoichiometry Calculator returns Mass of Product Formed of 137.1883. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Mass of reactant availableminimum 0 g
- 50 g
- Molar mass of the reactantminimum 0 g/mol
- 16.04 g/mol
- Coefficient of the reactantaccepts 1–20
- 1
- Coefficient of the productaccepts 1–20
- 1
- Molar mass of the productminimum 0 g/mol
- 44.01 g/mol
Results
- Mass of Product Formed
- 137.1883 g
- Moles of Reactant
- 3.117207 mol
- Moles of Product
- 3.117207 mol
- Mass Ratio of Product to Reactant
- 2.74377
- Reactant Needed per Gram of Product
- 0.36446 g
Step by step
- 1Values used
- 2Stoichiometry
- 3Mass of Product Formed= 137.1883 g
- 4Moles of Reactant= 3.117207 mol
- 5Moles of Product= 3.117207 mol
- 6Mass Ratio of Product to Reactant= 2.74377
- 7Reactant Needed per Gram of Product= 0.36446 g
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Stoichiometry calculated?
moles reactant → × (coefficient ratio) → moles product → × molar mass Stoichiometry always goes mass to moles, across by the coefficient ratio, then moles back to mass. Attempting to convert mass directly is wrong because mass ratios are not the reaction ratios.
Why does Stoichiometry matter?
The coefficient ratio is the whole content of a balanced equation, and getting it wrong invalidates every downstream figure.
What values do I need to enter?
This calculator takes 5 inputs: Mass of reactant available, Molar mass of the reactant, Coefficient of the reactant, Coefficient of the product, Molar mass of the product. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.