Chemical Equation Balancer

A balanced equation has the same number of each atom on both sides of the arrow, as required by the law of conservation of mass — atoms are rearranged in a reaction, never created or destroyed. Balancing finds the smallest whole-number coefficients that make both sides match.

Subscripts define the substance itself — changing H2O to H3O would describe a different chemical. Only the coefficients (the big numbers in front) may change, because they say how many molecules react without changing what the molecules are.

It builds a matrix of atom counts (one row per element, one column per molecule), then computes the null space of that matrix with exact fraction arithmetic — no rounding. The null vector gives the coefficient ratios, which are scaled to the smallest whole numbers.

Most single-step reactions, including formulas with parentheses like Ca(OH)2 and hydrates like CuSO4·5H2O. Write the arrow as ->, →, or =. Don't include coefficients in your input — the tool computes them. Charged species and half-reactions aren't supported.

First check every formula for typos — a wrong subscript or element symbol is the usual cause. If the formulas are right, the reaction as written may genuinely be impossible (for example H2 -> O2 can't balance because oxygen appears from nowhere).

Start with H2 + O2 -> H2O. Oxygen needs 2 on the right, so put 2 before H2O; now hydrogen needs 4 on the left, so put 2 before H2. The result, 2H2 + O2 -> 2H2O, has 4 H and 2 O on each side.