Most prosthetic and robotic feet are still far from reaching the functionality and versatility of the human foot. The adoption of a rigid and flat design prevents the foot from adapting to terrain obstacles, weakening the user’s stability. The SoftFoot is a recently presented robotic foot prototype designed to adapt its sole to ground unevenness. Nevertheless, this new foot still has some limitations, with no sensors and being completely passive. The exploitation of its adaptability requires novel sensor systems to estimate the distribution of forces on the contact surface. This study proposes a model-based approach to reconstruct the contact forces distribution, using only the knowledge of the foot shape as input. The foot model is formalized and analyzed as a grasping problem with a quasi-static approach in the sagittal plane with the hypothesis of elastic contact between the foot and the ground.