Balance a chemical equation automatically and see the correct stoichiometric coefficients.
The Chemical Equation Balancer takes an unbalanced chemical equation and calculates the correct whole-number stoichiometric coefficients needed to satisfy the law of conservation of mass — the same number of atoms of each element must appear on both sides of the equation. Balancing equations by trial and error is a core skill taught in every introductory chemistry course, but for equations with several different elements and compounds, manual trial and error can take several attempts to get right, and it is easy to end up with coefficients that are technically balanced but not in the simplest whole-number ratio.
To use it, type your equation using the format shown in the example: separate reactants and products with an arrow written as "->", separate multiple compounds on the same side with a plus sign, and write chemical formulas using standard capitalization and subscript numbers written as regular digits (for example, write water as H2O and oxygen gas as O2). Press "Balance Equation" and the tool sets up the underlying system of linear equations representing the conservation of each element, solves it mathematically, and displays the balanced equation with the correct coefficients placed in front of each compound.
Behind the scenes, balancing an equation is a linear algebra problem: each element that appears anywhere in the equation contributes one equation to a system, and the compounds' coefficients are the unknowns to solve for. This tool builds that system automatically from the formulas you enter and solves it to find the smallest possible set of whole-number coefficients, which is exactly the method taught conceptually in chemistry courses, just performed automatically rather than by hand.
This is useful for checking your own manual work after balancing an equation by trial and error, for quickly generating the balanced form of an equation you need for a stoichiometry calculation without spending time on the balancing step itself, and for building intuition by comparing several different equations and noticing patterns in how coefficients relate to the number of atoms involved. It is not, however, a substitute for understanding why conservation of mass requires balancing in the first place, which remains an important conceptual foundation for the rest of stoichiometry, limiting reagent calculations, and reaction yield problems that build on top of a balanced equation.
All parsing and solving happens locally using JavaScript in your browser, so no equation you enter, including one from an unpublished lab report, is transmitted anywhere.
Balancing more complex equations, particularly those involving several polyatomic groups or larger organic molecules, can occasionally require a wider search range of coefficients than smaller equations typically need; if the tool cannot find a solution within its default search range, try simplifying the formula notation or breaking a more complex reaction into smaller intermediate steps that are individually easier to balance and verify.
Once you have a balanced equation, it becomes the starting point for further stoichiometry work such as calculating limiting reagents, theoretical yield, or percent yield, all of which depend on having correct coefficients in place first; treat the balanced equation from this tool as the foundation for those next calculations rather than the final answer to a full stoichiometry problem on its own.
Use -> to separate reactants from products and + to separate multiple compounds on the same side, writing formulas with regular digits for subscripts, for example: CH4 + O2 -> CO2 + H2O.
It can balance most standard equations built from element symbols and simple formulas; extremely complex organic structures with many repeated groups may need to be simplified into standard chemical formula notation first.
The tool will confirm this by returning coefficients of 1 for every compound, or the simplest equivalent whole-number ratio if a non-1 ratio also balances the equation.
It shows the final balanced equation but does not walk through every intermediate algebra step; use it to check your own manual balancing work or to save time once you already understand the underlying method.
This tool balances atoms of each element in a standard molecular equation; balancing ionic or redox half-equations with charge balance requires additional steps beyond what this tool performs.
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