Chemical Equation Balancer
Balance chemical equations using a linear algebra approach with atom count checks.
How to enter an equation
Type the reactants on the left, products on the right, and put an arrow between them. Use plus signs between separate substances. Example: CH4 + O2 -> CO2 + H2O.
The balancer accepts ->, =>, =, and common typed arrow symbols. You may include state symbols such as (s), (l), (g), and (aq); the calculator ignores those labels when counting atoms.
Accepted input examples
| What you can type | Meaning |
|---|---|
| H2 + O2 -> H2O | Basic molecular equation |
| Fe(s) + O2(g) -> Fe2O3(s) | State symbols are allowed |
| CH4 + O2 = CO2 + H2O | Equals sign can be used as the arrow |
| Al + HCl => AlCl3 + H2 | Double-character arrow is accepted |
| CuSO4.5H2O -> CuSO4 + H2O | Hydrate dot notation can use a period |
| Na3PO4 + MgCl2 -> NaCl + Mg3(PO4)2 | Parentheses in formulas are supported |
Formula used
Example calculation
For H2 + O2 -> H2O, hydrogen and oxygen must have the same atom counts on both sides. The smallest whole-number coefficients are 2, 1, 2, so the balanced equation is 2H2 + O2 -> 2H2O.
Check: the reactant side has 4 H atoms and 2 O atoms. The product side also has 4 H atoms and 2 O atoms.
What this calculator does
The Chemical Equation Balancer is an online chemistry tool for students, teachers and science learners who want a fast result with visible reasoning. It is designed to support homework checking, classroom examples, laboratory preparation and exam revision. Instead of only displaying an answer, the page shows the formula used, the substituted values, a step-by-step calculation path and a plain-language explanation of what the result means.
The tool reads the formulas on each side of the equation, counts the atoms of every element, and solves for the smallest whole-number coefficients that make the counts equal. It supports common classroom formulas with element symbols, subscripts, parentheses, square brackets and hydrate dot notation. It also normalizes common arrow symbols and optional state labels to make input easier.
How to use this chemistry calculator
- Choose a quick example or select Custom equation.
- Type the unbalanced equation with
+between substances and an arrow between reactants and products. - Keep formula subscripts exactly as they belong in the compound, such as
H2OorAl2(SO4)3. - Click Calculate to see the balanced equation, coefficients and atom-count table.
- Use the atom-count table to confirm every element has the same count on both sides.
Chemistry explanation
A balanced chemical equation follows conservation of matter: atoms are not created or destroyed during an ordinary chemical reaction. The same elements must appear in equal numbers on the reactant and product sides.
Only coefficients are changed while balancing. Subscripts are part of the chemical formulas, so changing a subscript changes the substance. For example, changing H2O to H2O2 would turn water into hydrogen peroxide, which is a different compound.
State symbols such as (aq) and (g) describe physical state. They are useful in written equations, but they do not change atom counts, so the calculator removes them before balancing.
Common chemistry use cases
- Checking homework equations before stoichiometry calculations.
- Balancing combustion, synthesis, decomposition and double-replacement reactions.
- Preparing mole-ratio coefficients for limiting reagent problems.
- Verifying atom conservation after hand balancing.
- Generating clean balanced equations for class notes or lab reports.
Common mistakes
- Changing subscripts instead of coefficients.
- Forgetting to place
+between separate reactants or products. - Leaving out the arrow between reactants and products.
- Typing invalid element capitalization, such as
co2instead ofCO2. - Forgetting parentheses in polyatomic groups, such as
Mg3(PO4)2. - Using net ionic charge notation without spacing around plus signs. For best results, type molecular equations or keep ion separators spaced clearly.
Rounding, units and result checking
Balancing equations is a whole-number coefficient problem, so there are no measurement units to round. The final coefficients should be the smallest whole-number ratio. Always check the atom-count table: every element should show the same count for reactants and products before using the equation in stoichiometry.
Related Chemistry Tools
Chemical Equation Balancer FAQs
How to balance chemical equations?
Balancing a chemical equation is like balancing a kitchen recipe — you must have the same number of each kind of atom on both sides. Follow this five-step routine: (1) Write the correct unbalanced (skeletal) equation. (2) Count atoms of each element on both sides. (3) Balance metals first, then non-metals, then hydrogen, finally oxygen. (4) Adjust coefficients (never change subscripts!). (5) Verify by recounting. Always reduce coefficients to the smallest whole-number ratio. This obeys the Law of Conservation of Mass — atoms are neither created nor destroyed. Example: Fe + O2 → Fe2O3 becomes 4 Fe + 3 O2 → 2 Fe2O3
Why must chemical equations be balanced?
Because nature itself balances them. The Law of Conservation of Mass, given by Antoine Lavoisier, states that mass is neither created nor destroyed during a chemical change. An unbalanced equation would mean atoms appearing or disappearing — a violation of physics. Balanced equations also let us calculate the exact amount of reactants needed and products formed in stoichiometry problems, predict yields in industry, design safe reactions, and link mole ratios to volumes, masses and energy changes. Without balancing, chemistry would be guesswork.
How to write a balanced chemical equation?
Start by translating the word equation into formulae. For example, “Hydrogen reacts with oxygen to form water” becomes H2 + O2 → H2O. Now balance: oxygen has 2 on left and 1 on right, so put coefficient 2 in front of H2O, then balance hydrogen by placing 2 in front of H2. Add physical states: (s), (l), (g), (aq). Mention conditions like Δ (heat), pressure or catalyst above the arrow. Always check both sides have equal atoms and equal charges in case of ionic equations. 2 H2(g) + O2(g) → 2 H2O(l)
What is the balanced chemical equation for photosynthesis?
Photosynthesis is the wonderful process by which green plants prepare food using sunlight. Carbon dioxide from the air and water from the soil combine inside chloroplasts, in the presence of chlorophyll and sunlight, to produce glucose and release oxygen. The overall balanced equation is shown below. Notice how perfectly balanced it is: 6 carbons, 18 oxygens and 12 hydrogens on each side. This single reaction sustains almost all life on Earth. 6 CO2 + 6 H2O (sunlight, chlorophyll) → C6H12O6 + 6 O2
Which is a correctly balanced chemical equation?
A correctly balanced equation has three properties: (i) the same number of each kind of atom on both sides; (ii) the same total electric charge on both sides (important for ionic equations); and (iii) coefficients in their smallest whole-number ratio. For example, H2 + Cl2 → 2 HCl is correctly balanced. The equation H2 + Cl2 → HCl is not balanced because we have 2 H atoms on the left but only 1 on the right. Always recount after balancing.
What do the coefficients in a balanced chemical equation represent?
Coefficients are the most powerful piece of information in an equation — they tell us the mole ratio in which substances combine. Take 2 H2 + O2 → 2 H2O. The coefficients 2 : 1 : 2 mean: 2 moles of hydrogen react with 1 mole of oxygen to give 2 moles of water. They also represent the ratio of molecules and, for gases at the same T and P, the ratio of volumes. They do NOT represent mass directly; for mass we must multiply by molar masses.