An approach is presented to combine a system of criteria and combustion models into a computer tool for conservative estimates of possible pressure loads resulting from combustion of fuel-air mixtures. This approach is based on identification of characteristic combustion regimes by their relative severity, application of criteria to identify the strongest possible regime for particular initial conditions and geometry, and on development of appropriate three-dimensional models to describe flame propagation and loads for selected combustion regimes. A computer code (CREBCOM) was developed using this approach. Short descriptions of the code, criteria and models are given. The computer code was applied to simulate turbulent deflagration and detonation experiments at different scale and geometrical configurations. These experiments included tests with flame propagation in explosion channels (tubes) and large-scale tests in the RUT facility. Numerical simulations showed that such a code is able to give reliable estimations of overpressure for a wide range of combustion regimes, compositions and geometry.