<p>Projector-camera systems have numerous applications across diverse domains. Accurate calibration of both intrinsic and extrinsic parameters is crucial for these systems. Intrinsic parameters include focal length, distortion parameters, and the principal point, while extrinsic parameters encompass the position and orientation of the projector and camera. A non-overlapping projector-camera system is required in certain scenarios due to practical limitations, physical arrangements, or specific application requirements. These systems pose a more complex calibration challenge because the devices have no direct correspondences or overlapping fields of view, necessitating intermediate objects or methods. This paper proposes a calibration method for non-overlapping projector-camera systems using a planar mirror. The method involves a straightforward process that requires a calibrated camera and a separate mirror calibration step. In this setup, the projector displays a pattern on a planar calibration board, and the camera has an indirect view of this calibration board through the mirror. Using homography, 3D-2D correspondences of the projector are established, enabling the calibration of the system. This method is empirically evaluated using real-world setups and quantitatively assessed in a synthetic environment. The results demonstrate that the proposed method achieves precise calibration across various setups, proving its effectiveness. This approach is an easy-to-use and accessible calibration process for non-overlapping projector-camera systems, made possible by a mirror.</p>