Sandy beaches are well-known for their dynamic and complex environments. Traditional survey methods in these areas have limitations, such as requiring significant manpower, being time-consuming, and potentially expensive. These limitations have introduced the use of a more innovative and cost-effective, called Unmanned Aerial Vehicle (UAV). Generally, UAV Photogrammetry mapping requires Ground Control Points (GCPs). However, placing GCPs on beaches can be challenging due to accessibility issues and environmental factors. One practical method to overcome the issue is Post-Processing Kinematics (PPK) UAV Photogrammetry. The purpose of this study is to determine the optimal altitude for PPK UAV Photogrammetry beach mapping. The study uses CHCNAV AA450 for PPK UAV Photogrammetry and Light Detection and Ranging (LiDAR) mapping since the sensor has a built-in camera for aerial mapping. Three altitudes for PPK UAV Photogrammetry were selected, specifically 60 m, 100 m, and 140 m, over a horizontal distance of approximately 2 km. Data processing uses CoPre for LiDAR and Agisoft for PPK UAV Photogrammetry, while data analysis uses Global Mapper for volume estimation. The volume estimations calculated from Triangulated Irregular Network (TIN) and the results from PPK UAV Photogrammetry were compared to the result from LiDAR, as LiDAR can provide precise elevation data using high-resolution 3D point clouds acquired directly during data collection. The volume analysis demonstrates that the lowest altitude does not necessarily correspond to the optimal altitude for data collection. The accuracy assessment reveals that the 100 m altitude yields the most reliable results for volumetric measurements.