A jack extension system includes a mechanical jack that has a vertical support and a foot mounted on the vertical support. The foot is moved upwardly or downwardly on the vertical support. The vertical support has an upper end. A bracket is removably attached to the upper end of the jack. The bracket has an opening extending therethrough. A post has a bottom end and a top end. The bottom end comprises a coupler that is removably attached to the foot. The top end comprises a plate. The post extends through the bracket and the plate is abuttable against an object to be lifted.