Chemical Equation Balancer

Type a chemical equation and get the smallest whole-number coefficients that balance every element. It handles ionic equations, half-reactions and hydrates, and shows the working and reaction masses.

How to use

1. Type the equation into "Chemical equation", for example Fe + O2 = Fe2O3, or load one with the "Examples" buttons.
2. The result appears under "Balanced equation" with subscripts. Press "Copy equation" to copy it.
3. "Atom check" compares the atoms of each element on both sides, and "Working" shows the system of equations.
4. On "Masses", enter the mass of one substance to get the theoretical masses of the others.

How it works

• One equation is written per element (and for total charge in ionic equations), solved exactly with fractions and scaled to the smallest whole numbers.
• Write charges with ^, as in Fe^3+ or SO4^2-, and an electron as e-. Write hydrates as CuSO4·5H2O or CuSO4*5H2O. Element symbols are checked against all 118 elements.
• Masses are theoretical values that assume the reaction goes to completion. Atomic weights come from the IUPAC CIAAW abridged standard atomic weights (2024).

Questions and answers

How do you balance a chemical equation?

Put an unknown coefficient in front of each substance and require the same number of atoms of each element on both sides, then solve. For example, Fe + O2 → Fe2O3 becomes 4Fe + 3O2 → 2Fe2O3.

What is the balanced equation for burning methane?

CH4 + 2O2 → CO2 + 2H2O. Both sides have 1 carbon, 4 hydrogen and 4 oxygen atoms.

Why does it say the equation cannot be balanced?

An element appears on one side only, the charges do not match, or a formula is mistyped. The page names the elements found on one side only. Check capitals too: Co is cobalt, CO is carbon monoxide.

What does it mean when there is more than one answer?

The equation combines two or more independent reactions, so the coefficients depend on their ratio. The page shows one small whole-number balance and the independent reactions.