Eyebox performance is a fundamental factor used to characterize the overall performance of augmented reality (AR) and virtual reality (VR) eyewear. Conventional methods to map three-dimensional eyeboxes are time consuming and data intensive. Herein, we propose a method for rapid and accurate measurement of the eyebox in AR/VR displays. Our approach utilizes a lens that simulates key characteristics of the human eye, including pupil position, pupil size, and field of view, to obtain a representation of the eyewear's performance as perceived by a human user using single image capture. By combining a minimum of two such image captures, the complete eyebox geometry of any given AR/VR eyewear can be accurately determined with a level of accuracy comparable to that of slower, traditional methods. This method can potentially be used as a new metrology standard in the display industry.