Balance a chemical equation without changing its formulas
A chemical equation balancer finds the smallest whole-number coefficients that conserve every element between the reactant and product sides. Enter formulas such as H2, O2, and H2O with spaces around each plus sign. The result places coefficients before the formulas and leaves every subscript untouched, because changing a subscript would describe a different substance rather than balance the stated reaction.
This page is useful for homework checks, stoichiometric setup, and reviewing equations that contain parentheses or brackets. It accepts explicit ionic charges written with a caret, such as Fe^3+ or SO4^2-, and then conserves net charge as well as atoms. It does not decide which substances react, generate missing products, infer phases, or prove that the written reaction is chemically possible.
How exact algebra produces the coefficients
Each species becomes one unknown coefficient. For every element, the calculator builds an equation stating that the reactant atom total equals the product atom total. Charged equations add one more row for net electric charge. The resulting homogeneous system is solved with exact rational arithmetic, so a fraction created during elimination is not rounded into a false near-integer answer.
After solving, all fractions are multiplied by a common denominator and the integers are divided by their greatest common divisor. The page requires one unique ratio in which every entered species has a positive coefficient. If the formulas permit several independent ratios, require a zero coefficient, or have no nonzero solution, it asks you to add missing chemistry or remove unrelated species instead of selecting an arbitrary answer.
Work through a balancing example
For H2 + O2 → H2O, hydrogen conservation gives 2a = 2c and oxygen conservation gives 2b = c. The smallest positive integers satisfying both statements are a = 2, b = 1, and c = 2. The balanced equation is therefore 2H2 + O2 → 2H2O. The audit shows four hydrogen atoms and two oxygen atoms on each side.
A more complex entry such as Fe + O2 → Fe2O3 produces 4Fe + 3O2 → 2Fe2O3. Parentheses also remain part of the chemical identity: Ca(OH)2 contains one calcium, two oxygen, and two hydrogen atoms. Always use correct capitalization because Co means cobalt while CO represents carbon and oxygen, and the parser deliberately treats those as different formulas.
Check coefficients, atoms, and explicit charge
Read the conservation table before using the equation in a mole calculation. Every element row must show identical totals, and an ionic equation must also show identical net charge. Coefficients describe relative particles or moles, so multiplying every coefficient by the same number remains balanced, but the standard answer is the smallest positive whole-number ratio displayed by the calculator.
If a problem already shows coefficients, remove them before entering each formula; the calculator rejects leading coefficients and derives its own reduced ratio. Do not move a subscript into the coefficient position or omit a formula unit. For redox work in acidic or basic solution, the molecular species and charges must already be stated; a dedicated half-reaction method may be needed to determine missing H2O, H+, OH-, or electrons.
Equation scope, safe interpretation, and privacy
Conservation is necessary for a chemical equation but not sufficient to establish thermodynamics, kinetics, equilibrium, selectivity, physical state, or laboratory safety. A balanced equation can still describe a reaction that is negligible, hazardous, or dependent on unstated conditions. Use authoritative reaction information and a qualified procedure before connecting classroom stoichiometry to real chemicals, heat, pressure, or scale-up.
The values are calculated in the current browser tab. NexaCurrent does not upload the quantities, formulas, chemical names, element choices, or other information entered here, and no account is needed. Copying is a deliberate action after the answer and working are visible. Refreshing or leaving the page clears the current calculation, so keep a copied result if it is needed for later study.