Air & Fuel Calculators
Actual Air Requirement Calculator
Calculate the actual air a burner should be supplied, combining theoretical air requirement with an excess air margin.
Air Density Altitude Correction Calculator
Calculate air density at altitude using the International Standard Atmosphere model, useful for correcting combustion air calculations at elevation.
Air Preheater Effectiveness Calculator
Calculate combustion air preheater effectiveness from air inlet, air outlet, and hot gas inlet temperatures.
Air-Fuel Ratio (AFR) Calculator
Calculate the air-fuel ratio (AFR) from the mass of air and fuel supplied to a combustion process.
Combustion Air Blower Power Calculator
Calculate the actual motor power required for a combustion air blower from airflow, pressure rise, and blower efficiency.
Combustion Air Flow Calculator
Convert combustion air mass flow rate into volumetric flow rate using air density, for fan and duct sizing.
Combustion Air Temperature Rise Calculator
Calculate the temperature rise of combustion air from a given heat input, air mass flow rate, and specific heat capacity.
Combustion Air Velocity Calculator
Calculate combustion air velocity in a duct from volumetric flow rate and duct cross-sectional area.
Excess Air Calculator
Calculate excess air percentage from actual and theoretical air supplied to a combustion process.
Fuel Flow from AFR Calculator
Calculate fuel mass flow rate from a known air mass flow rate and target air-fuel ratio.
Fuel-Air Mixture Heating Value Calculator
Calculate the heating value per unit mass of the total air-fuel mixture, accounting for the air-fuel ratio.
Fuel-to-Air Ratio Calculator
Calculate the fuel-to-air ratio (FAR), the reciprocal of AFR, from fuel and air mass supplied to a combustion process.
Ideal Gas Air Density Calculator
Calculate air density from absolute pressure and temperature using the ideal gas law and the specific gas constant for dry air.
Lambda from AFR Calculator
Calculate lambda (air-fuel equivalence ratio) from actual and stoichiometric air-fuel ratios to classify mixture as rich, stoichiometric, or lean.
Primary Air Calculator
Calculate the primary air portion of total combustion air supplied for ignition and initial combustion.
Secondary Air Calculator
Calculate the secondary air portion of total combustion air, the remainder after primary air is accounted for.
Stoichiometric Air Requirement Calculator
Calculate the exact stoichiometric air requirement for complete combustion from a fuel's carbon, hydrogen, oxygen, and sulfur content.
Tertiary Air Calculator
Calculate tertiary air quantity from total combustion air and known primary and secondary air percentages.
Theoretical Air Calculator
Calculate theoretical combustion air from fuel mass and a known stoichiometric air-fuel ratio.
Volumetric Efficiency Calculator
Calculate engine volumetric efficiency (VE) from actual air intake volume and engine displacement volume.
The Ratio That Makes or Breaks Combustion
Every combustion process — from a car engine to an industrial furnace — depends on mixing fuel with the right amount of air. Too little air and fuel burns incompletely, wasting energy and producing soot; too much air and the process wastes heat carrying excess air through the system. These ten calculators cover the air-fuel ratio math that keeps combustion in the efficient middle ground.
Modern engines hover close to stoichiometric during cruising for the best balance of efficiency and emissions, shifting richer briefly under hard acceleration for extra power. The Air-Fuel Ratio (AFR) Calculator shows exactly where a given mixture sits relative to that 14.7:1 stoichiometric point, and the Excess Air Calculator quantifies how far a mixture strays from it.
Popular Air & Fuel Calculators
- Stoichiometric Air Requirement Calculator — finds the exact air quantity needed for complete combustion of a given fuel amount.
- Combustion Air Flow Calculator — converts a required air mass into a volumetric flow rate for burner sizing.
- Theoretical Air Calculator — calculates the minimum air needed for complete combustion, before any safety margin is added.
Diesel engines, worth noting, typically run leaner overall (excess air) across most operating conditions, using compression ignition rather than a spark — part of why diesel tends to be more fuel-efficient but produces different emission characteristics than gasoline.
Need the deeper combustion chemistry? See the Advanced Combustion Calculators, or check downstream exhaust composition in Emissions Calculators.