The utility model relates to a depthometer used with a drill bit, which comprises a body, a fastening mechanism and a cover. The body is structured into an adapting drill bit; the fastening mechanism connected to the body is structured to detachably connect the body to the drill bit; the cover is structured to be detachably connected to the body at one of a first position and a second position which are opposite to the boxy; the cover contacts with the surface of a workpiece at the first position to prevent the drilling amount of the drill bit drilling into the workpiece from surpassing a first depth; and the cover contacts with the surface of the workpiece at the second position to prevent the drilling amount of the drill bit drilling into the workpiece from surpassing a second depth different from the first depth. In addition, the utility model further relates to a complete set of appliances used with the drill bit and the drill bit used with the depthometer. The depthometer can be used with drill bits of various sizes to form holes for anchoring parts of various sizes. Moreover, the depthometer can be additionally connected onto the drill bit and detached from the drill bit without additional tools.