Production efficiency is a critical factor in enhancing competitiveness within the manufacturing industry. One of the primary barriers to achieving optimal efficiency is the Six Big Losses, which represent six major categories of productivity loss in production machinery. This study aims to identify and analyze the Six Big Losses on the Vacuum Forming Female machine at PT ABC. Operational data were collected from September to December 2024 and analyzed using a quantitative approach based on production metrics. The findings reveal that Idle and Minor Stoppage Losses are the most significant contributors to inefficiency, accounting for an average of 34% of total losses. These losses are primarily attributed to extended material waiting times and the unavailability of operators during critical periods. Reduced Speed Losses follow with a contribution of 33%, while Defect Losses account for 16%. Based on these results, the study recommends the implementation of a more structured preventive maintenance program, improved raw material supply chain management, and regular operator training. The implications of this research are expected to support data-driven decision-making and strategic efforts to enhance production efficiency in a competitive manufacturing environment.