Chemical Equation Balancer
Smallest whole-number coefficients instantly — with subscript rendering, an atom-count proof table & classic presets.
Classic reactions
💡 Balanced by solving the atom-conservation equations exactly (linear algebra over fractions) — the same coefficients you'd reach by trial and error, found instantly and provably minimal.
Balanced equation
4Fe + 3O2→2Fe2O3
Coefficients in gold — the smallest whole numbers that conserve every atom.
✅ Atom-count proof
Every element counted on both sides — this is what "balanced" means.
Fe
4 ⇄ 4
conserved ✓
O
6 ⇄ 6
conserved ✓
⚠️ The balancer conserves atoms; it can't know whether a reaction actually occurs, its conditions, or its states (s/l/g/aq) — add those from your chemistry knowledge.
⚖️Balanced instantly — and proven
Type any skeleton equation — Fe + O2 -> Fe2O3 — and get the smallest whole-number coefficients instantly, highlighted in gold with proper subscripts. Then the part that earns marks: an atom-count proof table showing every element tallied on both sides, so you can see conservation rather than trust it. Presets cover the classics from photosynthesis to the KMnO4 + HCl redox that ruins trial-and-error attempts.
📊Everything you'd want to know
- Accepts -> or = between sides; brackets and hydrates in formulas all work.
- Smallest whole-number coefficients, provably minimal — not just 'a' balance but 'the' balance.
- The atom-count proof: each element's total on both sides, green-ticked.
- Seven presets from making-water to a genuinely hard redox equation.
- Copy the balanced equation in one click.
🧮How it works
Balancing is a system of linear equations in disguise: every element contributes one "atoms in = atoms out" equation, and the coefficients are the unknowns. This balancer solves that system exactly (with fractions, then scales to smallest whole numbers) — the method that never guesses and never misses.
💡Balancing tips for exams
- Balance by hand in this order: metals → non-metals → hydrogen → oxygen; save O for last since it appears everywhere.
- Never change subscripts to balance — that changes the substance. Only coefficients may move.
- If you end with a fraction (e.g. 7/2 O2), multiply everything by the denominator.
- Always finish with an atom-count check — the exact table this tool draws for you.
💡 Frequently Asked Questions
How do I balance a chemical equation?+
Adjust coefficients (never subscripts) until each element has equal atoms on both sides. Work metals first, oxygen last. This balancer finds the smallest whole-number coefficients instantly and shows the per-element proof table.
What is the balanced equation for Fe + O2 → Fe2O3?+
4Fe + 3O2 → 2Fe2O3. Iron: 4 = 2×2 ✓; oxygen: 3×2 = 2×3 = 6 ✓. It's the rusting reaction and one of the balancer's one-click presets.
Why can't I change subscripts to balance an equation?+
Subscripts define the substance: H2O is water, H2O2 is hydrogen peroxide. Changing them balances a different (wrong) reaction. Only the coefficients — how many units of each substance — are yours to adjust.
What does a balanced equation actually tell you?+
The mole ratio of the reaction: 4Fe + 3O2 → 2Fe2O3 says four moles of iron consume three of oxygen. That ratio is the foundation of every stoichiometry calculation — pair this tool with our Mole Calculator.
Can this balance redox equations?+
Yes — any equation where atom conservation determines the coefficients, including tough ones like KMnO4 + HCl → KCl + MnCl2 + H2O + Cl2 (coefficients 2, 16, 2, 2, 8, 5). Try it from the presets.