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Chemical Equation calculator

Balance a chemical equation so that the number of atoms of each element is the same on both sides, as the law of conservation of mass requires.

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Chemical Equation calculatorChemical Equation

Auto-Balance · Atom Count · Molar Mass Engine

Quick Examples: H₂+O₂→H₂O CH₄+O₂→CO₂+H₂O Fe+O₂→Fe₂O₃ N₂+H₂→NH₃ C₃H₈+O₂→CO₂+H₂O KMnO₄+HCl Ca(OH)₂+H₃PO₄

A chemical equation is only honest when the same number of each atom stands on both sides, because atoms are rearranged in reactions, never created or destroyed. This tool balances equations for you, finding the smallest whole-number coefficients that conserve every element.

How to use this calculator

  • Enter the reactants and products with their chemical formulas (for example H2 + O2 → H2O).
  • Press calculate to see the balanced equation with its coefficients.

What balancing teaches beyond the answer

Coefficients are the recipe ratios of chemistry: they tell you the mole proportions in which substances react and form, which every later stoichiometry calculation stands on. Checking the balance atom by atom, as this tool does, is also the fastest way to catch a wrong formula, because an impossible balance usually means a formula, not the maths, is off.

Frequently asked questions

What are the rules for balancing an equation?
Change only coefficients, never the subscripts in formulas. Balance metals first, then non-metals, then hydrogen and oxygen last is a common workable order.
Why can I not change subscripts to balance?
A subscript is part of the substance's identity. Changing H2O to H2O2 does not balance water's equation; it swaps in a different chemical altogether.
What if fractions appear while balancing?
Multiply the whole equation through to clear them. Final balanced equations are conventionally written with the smallest whole-number coefficients.