Balancing Chemical Equations Calculator

Work out balancing chemical equations instantly with clear inputs, formula shown and shareable results.

About Balancing Chemical Equations Calculator

Hydrocarbon combustion balances by inspection in a fixed order: carbon sets the CO2 coefficient at x, hydrogen sets H2O at y/2, and oxygen is then whatever satisfies both, namely x + y/4. Propane (C3H8) therefore needs 5 O2 to give 3 CO2 and 4 H2O; when x + y/4 is a half-integer the whole equation is doubled to clear the fraction.

Formulas

Oxygen requirement

O2 = x + y/4

Products

CO2 = x, H2O = y/2

Worked example

With the default values below, Balancing Chemical Equations Calculator returns O2 Coefficient of 5.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Carbon atoms in the fuel (x in CxHy)minimum 1: 3
Hydrogen atoms in the fuel (y in CxHy)minimum 1: 8

Results

O2 Coefficient: 5.000
Balanced Equation: C3H8 + 5O2 -> 3CO2 + 4H2O
CO2 Coefficient: 3.00
H2O Coefficient: 4.00

Step by step

1Values used
2Oxygen requirement
3Products
4O2 Coefficient= 5.000
5Balanced Equation= C3H8 + 5O2 -> 3CO2 + 4H2O
6CO2 Coefficient= 3.00
7H2O Coefficient= 4.00

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is oxygen balanced last?

Oxygen appears in both products, so its requirement is only fixed once the carbon and hydrogen coefficients are known.

Does this handle incomplete combustion?

No - it assumes complete combustion to carbon dioxide and water. Producing carbon monoxide or soot lowers the oxygen requirement.