HomeCalculatorsStoichiometric Air–Fuel Ratio

Stoichiometric Air–Fuel Ratio

Theoretical AFR from elemental composition: AFR = (11.53·C + 34.34·(H − O/8) + 4.32·S) / 100, for mass fractions expressed in percent.

CombustionFuel

Carbon content% m/mHydrogen content% m/mOxygen content% m/mSulphur content% m/m

Stoichiometric AFR

13.58 -

Formula, assumptions, and limits

Ultimate analysis approach: C reacts with 32/12 × O₂ (= 2.67), H with 32/4 × O₂ (= 8), S with 32/32 × O₂ (= 1). Dividing by the oxygen mass fraction in air (0.232) gives AFR. HFO/VLSFO 14.0–14.5; MGO 14.6; LNG 17.2.

Symbol legend

Meaning	Unit	Source
Carbon mass %	% m/m	ultimate analysis
Hydrogen mass %	% m/m	ultimate analysis
Oxygen mass %	% m/m	ultimate analysis
Sulphur mass %	% m/m	ISO 8754
Stoichiometric air-fuel ratio	kg air / kg fuel	result