A method and apparatus for calibrating the output signal of a linear position detector without accessing the interior of the detector housing is provided. According to one exemplary embodiment, a magnet is selectively movable toward and away from the exterior of the electronics housing, and a sensor is provided within the housing for sensing the presence of the magnet. According to this embodiment, the linear position detector is calibrated by setting a movable marker at the desired position and pushing the magnet toward the housing. The sensor then detects the presence of the magnet, and a processor saves the position of the marker as a reference point. All future positions of the marker can then be scaled based upon the reference point. Thus, the linear position detector can be calibrated without the need for opening the electronics housing and potentially exposing the electronics components to moisture, contaminants, and/or static electricity. Preferably, the magnet is connected to a push button on a base, and the base includes an attachment mechanism, such as a clip for example, to attach the base to the position detector.