The system for vacuum formation of a dental appliance is a fully automated vacuum formation machine for dental appliances, such as retainers and the like. The system includes a base having a perforated top vacuum plate in communication with a vacuum source. A heating unit is positioned above the perforated top vacuum plate, and a controller is in communication with the heating unit and the vacuum source for selective actuation thereof. A holder releasably receives a thermoplastic plate. The holder is selectively positionable vertically over the perforated top vacuum plate and a dental impression cast mounted thereon. The holder is positioned by a linear actuator or the like, in communication with the controller. A sensor is positioned adjacent the perforated top vacuum plate for measuring the thermoplastic plate's thickness as it is molded about the dental impression cast, and is communication with the controller.