Enter a chemical equation and get it balanced instantly
Use + to separate compounds and = or -> to separate sides
2H2 + O2 = 2H2O
| Element | Before (L) | Before (R) | After (L) | After (R) | Status |
|---|---|---|---|---|---|
| H | 2 | 2 | 4 | 4 | Balanced |
| O | 2 | 1 | 2 | 2 | Balanced |
The Chemical Equation Balancer takes an unbalanced reaction you type in plain text, such as H2 + O2 = H2O or Fe + Cl2 -> FeCl3, and returns the smallest whole-number coefficients that satisfy the law of conservation of mass. It parses element symbols, subscripts, parentheses in polyatomic groups like Ca(OH)2, and hydrate dots, then shows the coefficient for every species on both sides.
It is built for high school and first-year college chemistry students checking homework, teachers preparing worked examples, and lab users confirming stoichiometry before a calculation. Because it also displays the step-by-step reasoning, it doubles as a study aid rather than just an answer box.
The tool treats balancing as a system of linear equations. Each distinct chemical species is assigned an unknown coefficient, and each element produces one equation stating that the number of its atoms on the left equals the number on the right. For example, for aA + bB -> cC, an element appearing in A and C gives an equation like (atoms in A) times a = (atoms in C) times c.
This system is solved over the rational numbers using Gaussian elimination on the resulting matrix. The solution is a ratio of coefficients rather than fixed values, so the balancer scales the answer by the least common multiple of the denominators and then divides by the greatest common divisor to produce the smallest set of whole numbers. This is why 2H2 + O2 -> 2H2O is returned instead of, say, 4H2 + 2O2 -> 4H2O.
If the element matrix has no non-trivial solution, the equation cannot be balanced as written, which usually means a formula is mistyped or a species is missing. Redox reactions balance by mass here but not by charge, since the matrix tracks atoms rather than oxidation states.
Type subscripts as ordinary numbers directly after the symbol, like H2O or CO2, and use parentheses for polyatomic groups such as Ca(OH)2 or Al2(SO4)3. No special formatting or superscript keys are needed.
Yes. You can separate the two sides with =, ->, or a Unicode arrow. Reactants and products within each side are joined with plus signs.
That result means no set of positive whole-number coefficients conserves every element, almost always because a formula is mistyped or a product or reactant is missing. Double-check each symbol, subscript, and that every element on one side also appears on the other.
It balances by mass, meaning atom counts on both sides match, and works for most redox reactions written as full formulas. It does not balance ionic half-reactions by electric charge, so add spectator species or use molecular formulas for best results.
No. The result is always reduced to the smallest whole-number coefficients by clearing denominators and dividing out the greatest common divisor, matching the convention used in textbooks.
Yes, it is completely free with no sign-up or usage limits. The balancing runs in your browser, so the equations you type are not uploaded or stored on a server.
Yes. It parses hydrate notation and long formulas such as C6H12O6, and combustion reactions like C8H18 + O2 -> CO2 + H2O balance correctly as long as the formulas are entered accurately.