In order to develop soot formation models for fuels in fires, a global Arrhenius equation for soot formation rate has been studied in terms of the mixture fraction, the fuel concentration in the fuel supply stream, the local gas density and the gas temperature. A procedure relying on modelling and experimental data determines the parameters for the soot formation rate by exploiting the physics and results in laminar smoke point flames corresponding to a given fuel. The main advantages of such an approach are its simplicity and applicability to fuels (solids or liquids) in fires as long as their smoke point height is known, whereas most of the previous studies focused on pure hydrocarbons.