||Protection of military vehicles against blast mine and high explosive in air is of a great concern in defence industry. Anti-Vehicle (AV) mines and Improvised Explosive Devices (IED's) are capable of inflecting damage to heavy vehicles. For the last decades, numerical simulation of blast wave propagation and its interaction with surrounding structures becomes more and more the focus of computational engineering, since experimental tests are very expensive and time consuming. This paper presents an experimental and numerical investigation of blast wave propagation in air, using an Arbitrary Lagrangian Eulerian (ALE) multi-material formulation developed in LS-DYNA with the contribution of the first author. To accurately capture peak pressure values of the shock wave, a very fine mesh, in the explosive material and the surrounding air mesh, is needed. For three dimensional problems, this condition leads to large size problems that can be CPU time consuming and not appropriate to run several times for engineering design purposes and structure analysis to resist blast loading. In order to calibrate numerical models to experimental data, using reasonable fine mesh, explosive masse scaling is used in this paper. Good correlations in terms of pressure and impulse between numerical results and experimental data were obtained when using the right combination of solution parameters and multiplying the explosive mass by an appropriate scaling factor. This procedure is commonly used in defence industry for structural design and to avoid running large scale problems.