Chemical Equation Balancer
Type any unbalanced equation — molecules, ions, brackets or hydrates — and get the smallest whole-number coefficients, an atom-count table that proves both sides match, and the working explained step by step.
To balance a chemical equation, change only the coefficients in front of each formula until every element has the same number of atoms on both sides. Never change a subscript. Iron rusting, Fe + O₂ → Fe₂O₃, balances as 4Fe + 3O₂ → 2Fe₂O₃, giving 4 iron and 6 oxygen atoms on each side.
Your equation
Separate substances with + and the two sides with =, -> or →.
MnO4^- Fe^3+ SO4^2-
Hydrates: CuSO4·5H2O or CuSO4.5H2O
States are kept: (s) (l) (g) (aq)
Electrons: e^-
Atom count check
Every element (and the total charge) must be equal on both sides.
| Element | Reactants | Products |
|---|
Conservation of mass
Total molar mass × coefficients on each side (g per “1 reaction”).
| Side | Working | Mass (g) |
|---|
How it was balanced
The algebraic method — the same idea works for every equation, however long.
Balance it yourself
Type a coefficient in front of each substance. The table below updates as you go.
Live atom count
| Element | Reactants | Products |
|---|
Why equations must be balanced
Atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass), so every atom on the left must appear on the right.
Write the skeletal equation
Reactants on the left, products on the right, correct formulae for each substance.
Press Balance
The tool finds the smallest whole-number coefficients — never change the formulae themselves.
Check the atom table
Each element’s count matches on both sides; for ions the total charge matches too.
Practise
Switch to “Try it yourself” and fill in coefficients with live feedback and hints.
Hit-and-trial method (NCERT)
- Start with the compound that has the most atoms.
- Balance one element at a time, leaving H and O (or free elements) for last.
- Change only the coefficients, never the subscripts — H₂O stays H₂O.
- Finally make sure the coefficients are the smallest whole numbers.
Algebraic method (used here)
Give each substance an unknown coefficient a, b, c… and write one equation per element:
a Fe + b O₂ → c Fe₂O₃
Fe: a = 2c, O: 2b = 3c. Put c = 1 → a = 2, b = 3/2. Multiply by 2 → 4Fe + 3O₂ → 2Fe₂O₃.
Balancing ionic equations
For ions, the total charge must also be equal. In MnO₄⁻ + 5Fe²⁺ + 8H⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O the charge is −1 + 10 + 8 = +17 on the left and +2 + 15 = +17 on the right.
Types of reactions
- Combination: A + B → AB (CaO + H₂O → Ca(OH)₂)
- Decomposition: AB → A + B (2H₂O → 2H₂ + O₂)
- Displacement: A + BC → AC + B (Fe + CuSO₄ → FeSO₄ + Cu)
- Double displacement: AB + CD → AD + CB
- Combustion: fuel + O₂ → CO₂ + H₂O + heat
Chemical Equation Balancer — your questions
How do you balance a chemical equation step by step?
Write the skeletal equation, then count the atoms of each element on both sides. Start with the compound that has the most atoms and balance one element at a time, leaving hydrogen, oxygen and free elements until last. Adjust only the coefficients, never the subscripts, and finish by reducing them to the smallest whole numbers.
Why must a chemical equation be balanced?
Because of the law of conservation of mass: atoms are neither created nor destroyed in a chemical reaction, so every atom present in the reactants must appear in the products. An unbalanced equation claims that matter appeared or vanished. A balanced equation also lets you work out reacting masses and mole ratios correctly.
How do you balance C₃H₈ + O₂ → CO₂ + H₂O?
Balance carbon first: 3 carbons on the left need 3CO₂. Then hydrogen: 8 hydrogens need 4H₂O. That gives 3 × 2 + 4 = 10 oxygen atoms on the right, so you need 5O₂ on the left. The balanced equation is C₃H₈ + 5O₂ → 3CO₂ + 4H₂O, a typical combustion reaction.
Can I change the formula of a substance to balance an equation?
No. Changing a subscript changes the substance itself — H₂O is water but H₂O₂ is hydrogen peroxide, a completely different compound. You may only place a coefficient in front of a formula, which means taking more molecules of the same substance. This is the single most common mistake in exams.
How do you balance an ionic equation?
Balance the atoms of every element first, then make the total charge equal on both sides. In MnO₄⁻ + 5Fe²⁺ + 8H⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O the left-hand charge is −1 + 10 + 8 = +17 and the right-hand charge is +2 + 15 = +17, so both atoms and charge balance.
What are the main types of chemical reactions?
Combination (A + B → AB), decomposition (AB → A + B), displacement (A + BC → AC + B), double displacement (AB + CD → AD + CB) and combustion (fuel + O₂ → CO₂ + H₂O + heat). Oxidation and reduction, which happen together as redox, describe the gain and loss of oxygen or electrons.
What do (s), (l), (g) and (aq) mean in an equation?
They are state symbols: (s) solid, (l) liquid, (g) gas and (aq) aqueous, meaning dissolved in water. Board answers usually expect them in the final balanced equation, along with conditions such as heat, sunlight or a catalyst written above the arrow. Any state symbols you type here are kept in the balanced result.