Air-Fuel Ratio (AFR) Calculator
Calculate air-fuel ratio for combustion engines at 14.7:1 stoichiometric. Free automotive calculator.
Most common automotive fuel. Stoichiometric AFR 14.7:1. Typical lambda range 0.7–1.2.
λ < 1 = rich, λ = 1 = stoichiometric, λ > 1 = lean. Typical range: 0.5–2.0
About This Calculator
Calculate air-fuel ratio for combustion engines at stoichiometric 14.7:1. Free online automotive calculator for engine tuning and efficiency analysis.
This free online calculator is part of Calculys comprehensive tool suite. Results update instantly and can be shared via URL.
How It Works
Enter your values and click Calculate. The tool uses validated formulas to compute accurate results with interactive charts and a detailed breakdown table.
Frequently Asked Questions
What is the ideal air-fuel ratio?
14.7:1 (lambda = 1.0) for gasoline. 14.7 kg of air per 1 kg of fuel. This is the stoichiometric ratio for complete combustion.
What happens if AFR is too rich?
Too much fuel: wasted fuel, carbon deposits, reduced efficiency, increased emissions. Rich = AFR < 14.7, lambda < 1.0.
What happens if AFR is too lean?
Too much air: engine runs hot, risk of detonation/knock, reduced power, potential engine damage. Lean = AFR > 14.7, lambda > 1.0.
What are AFRs for different fuels?
Gasoline: 14.7. Diesel: 14.5. Ethanol (E85): 9.8. Methanol: 6.4. Propane: 15.5. Natural gas: 17.2.
What is lambda?
Lambda = Actual AFR / Stoichiometric AFR. Lambda 1.0 = perfect stoichiometric. 0.85 = rich. 1.15 = lean.