The prosthetic foot (1) is a lamina of composite material with a characteristic J-shape, fixable by a TT bracket (2) directly to a socket (3) containing the stump, i.e. the residual part of the amputated lower limb, in the case of users with transtibial amputations, or to a TF bracket (2a) itself fixable to a mechanical knee (G) fixable to a socket (3a), in the case of users with transfemoral amputations. Said socket (3 or 3a) has a main axis (5) defined by the loading straight line by which the user, after applying the prosthesis, discharges body weight in the static position, and passing through a point (4) identifying the femoral epicondyle.