Chemical Equation Balancer

Balance chemical equations automatically with the smallest whole-number coefficients, and check the atom count.

Unbalanced equation	C3H8 + O2 = CO2 + H2O

Unbalanced equation

Use = or → between sides and + between species. Case matters (Co ≠ CO).

Balanced

C3H8 + 5O2 → 3CO2 + 4H2O

Atoms of every element are equal on both sides, with the smallest whole-number coefficients.

Atom check

Element	Reactants	Products
C	3	3
H	8	8
O	10	10

About the Chemical Equation Balancer

Type the reactants and products separated by + with = or → between the sides, for example C3H8 + O2 = CO2 + H2O. The balancer finds the smallest whole-number coefficients.

Mass is conserved, so each element must have the same number of atoms on both sides. The balancer writes one equation per element and solves for the coefficients exactly with fractions (linear algebra), then scales to the smallest whole numbers. Charges and states (s, l, g, aq) aren't handled; leave them out.

The formula

Solve A·x = 0 for the smallest positive integer x

Worked example

Burning propane: C3H8 + O2 → CO2 + H2O

3 C on the left needs 3 CO2; 8 H needs 4 H2O
That's 10 O on the right, so 5 O2
C3H8 + 5O2 → 3CO2 + 4H2O

Questions people ask

Why are subscripts never changed?

Changing a subscript changes the substance; only coefficients change.

What about ionic equations?

Balance the charges separately; this tool balances atoms only.