Accurate and regular calibration of measuring instruments plays a vital role in maintaining product quality and the safety of industrial processes. In busy workshops, prioritizing the calibration of instruments is of great importance. This paper presents a simple and practical model named ABCD, which categorizes measuring instruments into four groups based on their importance and risk. Category A includes critical instruments, category B important instruments, category C ordinary instruments, and category D low-importance or inactive instruments. This model enables optimal resource allocation, cost reduction, and enhancement of accuracy and safety. The advantages, challenges, and future development suggestions of the model are also discussed. The results demonstrate that the ABCD model is an effective and implementable management framework that can contribute to improving quality and productivity in industrial workshops.