Code-based methods can only be used to determine the wind loading on single-plate billboards in the normal wind direction. No simplified methods are available to estimate the drag force coefficient for single-plate and two-plate billboards for various aspect ratios, clearance ratios and wind attack angles. Using the experimental types of research on single-plate billboards available in the literature, a database was created for the drag force coefficient, for various aspect ratios, clearance ratios and wind attack angles. In the case of two-plate billboards, a very limited number of experimental data have been reported. Hence, Computational Fluid Dynamics (CFD) Simulations were performed to investigate the variation of drag force coefficient, for various aspect ratios, clearance ratios and wind attack angles. The CFD modeling procedure was validated with the experimental results available in the literature. Two separate regression equations were developed to predict the drag force coefficients for the required aspect ratios, clearance ratios and wind angle for single-plate and two-plate billboards. The maximum torsion about the base can be estimated by multiplying the maximum drag force by 18% of the billboard width for single-plate billboards and 21% of the billboard width for two-plate billboards.