Science & Environment
Combustion Air-to-Fuel Ratio Calculator
Estimate the stoichiometric air-to-fuel mass ratio for common fuels burned in air.
Your inputs
Change any value to update the result instantly.
Stoichiometric AFR
17.19 :1 (air:fuel)
Actual AFR with excess air
18.91 :1
Excess air
10 %
Equivalence ratio (φ)
0.909
Formula and working
AFR_stoich = mass of air ÷ mass of fuel for complete combustion
- 1
Collect the inputs
Fuel type = 1; Excess air = 10 %
- 2
Apply the formula
AFR_stoich = mass of air ÷ mass of fuel for complete combustion
- 3
Result
Stoichiometric AFR = 17.19 :1 (air:fuel)
Frequently asked questions
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Report a mistake or request an improvement
Tell us if a formula, unit, explanation, or result needs attention. Your message will include this calculator’s name and page.
Related calculators
HHV vs LHV Fuel Heating Value Calculator
Convert between higher heating value (HHV) and lower heating value (LHV) based on hydrogen content.
Battery Energy Density Calculator
Calculate gravimetric (Wh/kg) and volumetric (Wh/L) energy density of a battery pack.
Battery State of Charge from Open-Circuit Voltage
Estimate battery state of charge (SOC) from a measured open-circuit voltage using a linear model.
Biogas Anaerobic Digestion Methane Yield Calculator
Estimate methane yield and energy potential from anaerobic digestion of organic waste per ton.
Biomass Gasification Syngas Energy Output Calculator
Estimate the syngas volume and energy output from gasifying a quantity of biomass.
Building Envelope Heat Loss Calculator
Calculate conductive heat loss through a building envelope element using U-value, area and temperature difference.