Chemical Equation Balancer
Balance a chemical equation automatically.
Enter an unbalanced equation using '->' (or '=') as the arrow and '+' between compounds, e.g. 'H2 + O2 -> H2O'. The balanced equation with integer coefficients is computed instantly.
Learn more
What it does
A balanced chemical equation has equal numbers of each atom on both sides. The balancer finds the smallest whole-number coefficients that satisfy this, so you can read exact reactant and product ratios. Balancing is the first step of every quantitative calculation: without it, mole ratios are undefined and no yield or limiting-reagent analysis is possible.
How it works
It sets up one conservation equation per element (atoms in = atoms out), builds a stoichiometric matrix, and solves for coefficients via linear algebra (null space). The smallest integer solution gives the balanced equation. Because the system is solved for the null space, the result is always the smallest integer coefficient set; fractional partial solutions are scaled up automatically. Redox equations are balanced by atom count as usual — electron balance is implied by correct atom balancing.
Worked example
H₂ + O₂ → H₂O. Balancing gives 2 H₂ + O₂ → 2 H₂O: 4 H and 2 O on each side. Enter 'H2 + O2 -> H2O' and the tool returns the coefficients 2 : 1 : 2. A combustion check: C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O balances 3 C, 8 H and 10 O on each side. Enter 'C3H8 + O2 -> CO2 + H2O' and the tool returns 1 : 5 : 3 : 4.
When to use it
Use it for stoichiometry calculations, lab prep and titrations, predicting product amounts, and checking that an equation you wrote is atom-balanced. Teachers can generate practice problems with it, students can verify homework, and experimentalists use it as the entry point to the stoichiometry calculator when scaling a reaction.
FAQ
- What format should I use for the equation?
- Write reactants and products separated by '->' (or '='), with compounds joined by '+'. Example: H2 + O2 -> H2O. Subscripts are written inline, like H2O or Fe2(SO4)3.
- Does it handle charges and ions?
- It balances atoms; it works for neutral and ionic species as long as the formulas are valid, but it balances by atom count and does not check redox or charge separately.
- Why do some equations not balance?
- An equation only balances if the same atoms appear on both sides. If an atom is missing on one side (or the formula is wrong), no integer coefficients exist — check your formulas first.
- Can it balance reactions with multiple steps?
- It balances a single overall equation. For multi-step or redox reactions, write the net overall equation; the tool finds the smallest whole-number coefficients that conserve every element.