Chemical Equation Balancer
Balance any chemical equation, including redox and combustion reactions, and see the atom count of every element on both sides.
What this calculator does
Type an unbalanced equation such as H2 + O2 -> H2O and get the smallest whole-number coefficients, with a table that counts every element on each side.
When you need it
Every stoichiometry, yield or thermodynamics problem needs a balanced equation first. Balancing is also the first step when checking that a reaction is physically possible.
Formulas
- Atoms of each element on the left = atoms of that element on the right
- Charge on the left = charge on the right (for ionic equations)
How to use it
- Type the equation with an arrow, for example C3H8 + O2 -> CO2 + H2O.
- Press Enter to balance it.
- Check the element table: both columns should match.
Worked example
Balance the combustion of propane: C3H8 + O2 → CO2 + H2O.
- Carbon: 3 C on the left, so put 3 in front of CO2
- Hydrogen: 8 H on the left, so put 4 in front of H2O
- Oxygen: 3 × 2 + 4 = 10 O on the right, so put 5 in front of O2
Answer
C3H8 + 5 O2 → 3 CO2 + 4 H2O.
Common mistakes
- Changing a subscript instead of a coefficient, which changes the substance.
- Balancing oxygen and hydrogen first in combustion; do carbon first.
- Leaving fractional coefficients without clearing them.
Related tools
Frequently asked questions
Why do equations have to be balanced?
Atoms are not created or destroyed in a chemical reaction, so every element must have the same count on both sides.
Can coefficients be fractions?
They can be used while working, but the final equation should use the smallest whole numbers.
How do you balance a redox equation?
Balance atoms and charge, either with half-reactions or by solving for coefficients as the calculator does.