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Chemical Equation Balancer

Enter an unbalanced equation with ->, → or = as the arrow. The balancer finds the smallest whole-number coefficients and proves the result with an atom-count table for both sides.

Try:

Why equations must be balanced

The law of conservation of mass says atoms are never created or destroyed in a chemical reaction — only rearranged. A balanced equation is simply an honest equation: every atom entering on the left comes out somewhere on the right. An unbalanced equation describes something physically impossible.

The golden rule

Adjust coefficients (2H₂O ✓) — never subscripts (H₂O → H₂O₂ ✗ changes the substance)

How coefficients work

A coefficient multiplies the entire formula after it: 3Ca(OH)₂ means 3 calcium atoms, 6 oxygens and 6 hydrogens. Coefficients tell you the ratio of molecules reacting — 2H₂ + O₂ → 2H₂O reads “two hydrogen molecules react with one oxygen molecule to give two water molecules”.

Balancing combustion by hand

Balance C₃H₈ + O₂ → CO₂ + H₂O.

  1. Balance C first: 3 carbons → 3CO₂.
  2. Balance H next: 8 hydrogens → 4H₂O.
  3. Count O on the right: 6 + 4 = 10 → 5O₂ on the left.

Answer: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Common mistakes

⚠ Common mistake: Changing subscripts to force a balance — that changes the chemical identity, not the amount.
⚠ Common mistake: Leaving a common factor: 4H₂ + 2O₂ → 4H₂O should be simplified to 2H₂ + O₂ → 2H₂O.
⚠ Common mistake: Forgetting diatomic elements: oxygen gas is O₂, not O; same for H₂, N₂, F₂, Cl₂, Br₂, I₂.

For the full manual method with more examples, see How to Balance Chemical Equations.

Frequently asked questions

What arrow symbols does the balancer accept?

->, →, => and = all work. Both sides are split on + signs, so write each substance separated by plus symbols.

Why does it say my equation is impossible?

Usually an element appears on only one side — often from a typo in a formula. Every element must exist on both sides for mass to be conserved.

Does the balancer handle ionic charges?

It balances atoms, which covers standard schoolwork. Redox equations balanced by half-reactions (with electrons) need the manual half-reaction method.

Related chemistry tools

Stoichiometry CalculatorConvert between grams and moles of any two substances in a balanced equation using mole ratios.Limiting Reactant CalculatorFind the limiting reactant, theoretical yield and leftover excess for any balanced reaction.Molar Mass CalculatorCalculate the molar mass of any chemical formula with a full element-by-element breakdown and percent composition.

Learn the concepts

How to Balance Chemical EquationsLearn to balance chemical equations step by step using the counting method, with combustion and metal-acid examples plus the most common mistakes.Stoichiometry Step-by-StepA clear method for stoichiometry: balance the equation, convert to moles, apply the mole ratio, convert back. Includes full worked examples.How to Read Chemical FormulasDecode any chemical formula: element symbols, subscripts, parentheses, coefficients and hydrate dots — with H2O, Ca(OH)2 and CuSO4·5H2O examples.