A stoichiometric mixture is a mixture of fuel and air that contains the exact amount of air required for perfect combustion of the fuel. This perfect ratio of fuel and air in the mixture is called the stoichiometric ratio.

This article will shed some light on what a stoichiometric mixture is and how it affects the engine.

An air-fuel ratio is a dimensionless number that expresses the ratio between the actual amount of air in the mixture and the theoretical amount (stoichiometric amount) of air corresponding to the fuel used. The coefficient, named in English as the Air-Fuel Ratio, is denoted by the Greek letter λ (lambda).

The coefficient defined in this way is mainly used in the field of internal combustion engines because it is a necessary parameter for the preparation of the mixture. The air-fuel ratio thus thoroughly expresses the mixture's richness level. Each fuel needs a different amount of air for its perfect combustion.