A system and method for calibration of golf shots is provided. Specifically, a tool for providing a reference target superimposed over a magnified image of the cup for calibration purposes is provided. An optical putter calibration tool may include an eye lens; an object lens; a target lens; a beam splitter; and a target reticle. The eye lens, the object lens, the target lens, the beam splitter and the target reticle may be integrated in a shaft of a golf club, such as a putter, for providing a simultaneous magnified view and projecting a reticle image. Comparison of the reticle image and the magnified view may provide a reading of a playing surface characteristic.