Chemical Equation Balancer
Balance chemical equations automatically. Enter an unbalanced equation and get the balanced version.
How to Use the Chemical Equation Balancer
- Type the unbalanced equation into the input field, e.g. Fe + O2 = Fe2O3.
- Separate reactants and products with plus signs (+) and use = as the reaction arrow.
- Click Balance — the calculator finds the smallest integer coefficients that satisfy atom conservation.
- Review the balanced equation and the verification table showing atom counts on each side.
Quick Reference
| From | To |
|---|---|
| H2 + O2 = H2O | 2H2 + O2 = 2H2O |
| Fe + O2 = Fe2O3 | 4Fe + 3O2 = 2Fe2O3 |
| CH4 + O2 = CO2 + H2O | CH4 + 2O2 = CO2 + 2H2O |
| N2 + H2 = NH3 | N2 + 3H2 = 2NH3 |
| C + O2 = CO2 | C + O2 = CO2 |
| Al + HCl = AlCl3 + H2 | 2Al + 6HCl = 2AlCl3 + 3H2 |
Use Cases
- •Balancing reactions for chemistry homework and exam preparation.
- •Verifying handwritten equations before performing stoichiometric calculations.
- •Teaching and demonstrating the law of conservation of mass in classroom settings.
- •Quickly checking complex multi-element reactions in research and lab work.
Formula
A balanced chemical equation obeys the law of conservation of mass: the number of atoms of each element must be equal on both sides of the reaction arrow. Balancing is achieved by finding the smallest set of integer coefficients for each reactant and product such that atom counts match on both sides.
Frequently Asked Questions
Why must chemical equations be balanced?
The law of conservation of mass states that matter cannot be created or destroyed. In a chemical reaction, the total number of atoms of each element must be the same before and after the reaction. An unbalanced equation violates this law and cannot be used for stoichiometric calculations.
How does the balancer work?
The balancer sets up a system of linear equations — one equation per element — where the unknowns are the stoichiometric coefficients. It then solves this system using linear algebra to find the smallest positive integer solution. If no integer solution exists, the equation format may be incorrect or the reaction may not be chemically valid.
What equation format should I use?
Write reactants and products separated by a plus sign (+) and use an equals sign (=) to separate the two sides. For example: Fe + O2 = Fe2O3. Element symbols must start with a capital letter. Subscript numbers follow the element symbol directly (e.g., O2, Fe2O3). Parentheses are supported for polyatomic groups: Ca(OH)2.