Combustion Reaction Calculator

Your details

Choose a common fuel to auto-fill the atom counts, or pick Custom to enter your own.
Number of carbon atoms per molecule of fuel (e.g., 3 for propane C3H8).
Number of hydrogen atoms per molecule of fuel (e.g., 8 for propane C3H8).
Number of oxygen atoms already in the fuel molecule. Use 0 for pure hydrocarbons.
Balance gives stoichiometric coefficients. Moles/Grams also computes actual product amounts.
Balanced equation
C3H8 + 5O2 -> 3CO2 + 4H2O

Complete combustion reaction with smallest whole-number coefficients

O2 coefficient5
CO2 coefficient3
H2O coefficient4
Molar mass of fuel44.097g/mol
Stoichiometric AFR15.64
CO2 emission factor2.994kg CO2/kg fuel
Higher heating value54MJ/kg
O2 in (mol)5
CO2 out (mol)3
H2O out (mol)4

Balanced: C3H8 + 5O2 -> 3CO2 + 4H2O

  • The stoichiometric air-fuel ratio is 15.64:1. For every kilogram of C3H8 burned, 15.6 kg of air are needed.
  • The carbon dioxide emission factor is 2.994 kg CO2 per kg of fuel, set by the carbon content alone. Combustion efficiency improvements cannot reduce this ceiling.
  • The estimated higher heating value is 54.0 MJ/kg (Dulong formula). This is the gross chemical energy available assuming all water condenses.

Next stepSwitch the calculation mode to "Amounts from moles of fuel" or "Amounts from grams of fuel" to scale all reactant and product quantities to your specific batch size.

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