Equation Balancer

Balance chemical equations online with a step-by-step solution and the electron balance for redox reactions.

Separate substances with “+” and the two sides with “=” or “->”: Fe + O2 = Fe2O3. You don't need to write coefficients — the calculator finds them.

Test yourself

The chemical equation balancer finds the coefficients of a reaction equation and shows the solution: the system of atom balance equations, its solution and a check. For redox reactions it also builds the electron balance with the oxidizing and reducing agents and the numbers of electrons lost and gained.

How to enter an equation

Separate substances with “+” and the sides with “=”, “→” or “->”: KMnO4 + HCl = KCl + MnCl2 + Cl2 + H2O. You don't need coefficients; if you write them, the calculator recalculates them.

The algebraic method

The coefficients are denoted by letters a, b, c… For each element the number of atoms on the left equals the number on the right, which gives a system of linear equations. One letter is set to 1, the others are found, and all are multiplied by the common denominator to get the smallest whole numbers.

Example. aFe + bO₂ = cFe₂O₃: Fe: a = 2c, O: 2b = 3c. With c = 1: a = 2, b = 3/2; multiply by 2 — 4Fe + 3O₂ = 2Fe₂O₃.

Electron balance

If oxidation states change, the reaction is a redox reaction. The reducing agent loses electrons (is oxidized), the oxidizing agent gains them (is reduced). The electrons lost equal the electrons gained, so the multipliers come from the least common multiple.