Balancing Formulas Calculator
Balancing formulas calculator works out Balanced equation and Stoichiometric coefficients from Chemical equation. The default figures on this page give balanced equation of 4Fe + 3O2 → 2Fe2O3; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
2 steps
- Balanced equation: 4Fe + 3O2 → 2Fe2O3
- Molar masses (IUPAC 2021 abridged, dataset ciaaw-2024-abridged + nist-awic-ame2020): M(Fe) = 55.845 g/mol; M(O2) = 31.998 g/mol; M(Fe2O3) = 159.687 g/mol
Stoichiometric coefficientstable
Reactantstable
| formula | coefficient | molarMass |
|---|---|---|
| Fe | 4 | 55.845 |
| O2 | 3 | 31.998 |
Productstable
| formula | coefficient | molarMass |
|---|---|---|
| Fe2O3 | 2 | 159.687 |
Figures from IUPAC atomic weights, 2024 edition, checked 31 August 2026. Its 4 worked examples are re-run on every release, last on 15 September 2026. What changed · how reference data is kept current
Sources and references
3 sources
What the balancing formulas calculator calculates
Balances a chemical equation, identifies the limiting reagent from the amounts of each reactant, and reports the theoretical yield, the leftover excess reactant and the percent yield.
How to use this balancing formulas calculator
Enter Chemical equation. Balanced equation updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Balanced equation, Stoichiometric coefficients and Limiting reagent.
The method follows OpenStax Chemistry 2e, section 4.3 Reaction Stoichiometry, OpenStax Chemistry 2e, section 4.4 Reaction Yields and IUPAC Compendium of Chemical Terminology (Gold Book), "stoichiometric number".
What you can compare
Change one input at a time to see how it affects Balanced equation, Stoichiometric coefficients and Limiting reagent. The inputs you can vary are Chemical equation.
Understanding Balanced equation, Stoichiometric coefficients and Limiting reagent
Yields assume the written reaction goes to completion with pure reactants and no competing reaction. Confirm the reaction, purity and product basis before relying on the figure for laboratory or process work.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
What is the formula for balancing equations?
On the figures this page opens with, the balanced equation is 4Fe + 3O2 → 2Fe2O3. No single number fits everyone: it follows Chemical equation, so enter your own above and the answer updates as you type.
Is there a good app for balancing chemical equations?
Balances a chemical equation, identifies the limiting reagent from the amounts of each reactant, and reports the theoretical yield, the leftover excess reactant and the percent yield. Put your own figures in above and the working updates beside the result. For scale, the default figures on this page give 4Fe + 3O2 → 2Fe2O3.
What's the trick to balancing equations?
Balances a chemical equation, identifies the limiting reagent from the amounts of each reactant, and reports the theoretical yield, the leftover excess reactant and the percent yield. On this page it is computed from Chemical equation and shown as Balanced equation, Stoichiometric coefficients and Limiting reagent.
What information do I need for the balancing formulas calculator?
You need Chemical equation. The page opens with default figures that give balanced equation of 4Fe + 3O2 → 2Fe2O3, so you can see the scale before entering your own.
What does this balancing formulas calculator show?
It shows Balanced equation, Stoichiometric coefficients, Limiting reagent, Extent of reaction, Product reported, Theoretical yield, Percent yield and Reactants, with the working and any warnings for your entries.
Can I check how the balancing formulas calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.