In the laser forming process, the effect of workpiece size, including variations in width and length, plays a crucial role in determining product quality. To better understand the deformation behavior and obtain the desired bending angle with varying workpiece sizes, the size effect on laser forming of Al 6061-T6 aluminium alloy has been investigated. Due to the fact that Al 6061-T6 alloy sheets have more deformability and high strength properties, they have been studied in this paper. A three-dimensional numerical model that considers temperature-dependent properties of the material, and convection-radiation heat losses is constructed to investigate the sheet deformation. The numerical model is verified by performing experimental tests under the considered operating conditions. The suggested model is found to be in reasonable agreement with the experimental findings, and it is shown to have a maximum error less than 8 % when predicting the bend angle. Computed results through the numerical model show that the bending response is increased with the increase in workpiece width; however, it is marginally affected with workpiece length. Based on simulation results, the edge effect is also explored in relation to workpiece size. Edge effect increases as sheet width increases; whilst it decreases as sheet length increases. This investigation will be helpful in laser-based forming industries for obtaining desired bending of Al 6061-T6 sheets.