We have simulated dry and wet oxidation of silicon taking into account the emission of a large number of silicon species from the interface that governs the silicon-oxidation rate. The silicon emission model enables the simulation to be done by use of the oxidant self-diffusivity in the oxide with a single activation energy. Using a unified set of physically reasonable parameters, the whole range of oxide thickness for both dry and wet oxidation is fitted in a wide range of oxidation temperatures (800−1200^oC) and oxygen pressures (1−20 atm) for both (100) and (111) silicon substrates without any empirical modifications.