With the aim of optimizing the stamp geometry, a refined model for simultaneous calculation of the resist viscous flow in nanoimprint lithography (NIL) and the stamp/substrate deformation has been introduced. This model has been realized in the IMPRINT software. The software is designed for use on standard personal computers and provides results well suited for quantitative predictions of the residual resist thickness in NIL. A very good agreement between simulation and experimental results has been obtained. The results confirm the potential of the IMPRINT software as an efficient tool for the reduction of the stamp bending.