Several studies have shown that quality defect costs make up a significant portion of a company's revenue, typically between 10 and 30 percent. Quality defect costs arise from defects in a company's products or processes. Unfortunately, a large portion of these costs disappears because companies typically only consider visible costs such as material costs. The company in the study primarily bases its investment decisions on the potential time savings that can be achieved through investments in machinery. However, focusing only on time savings is insufficient because there are other costs that need to be considered to make a more complete calculation of the total benefits. This lack of information affects the company's investment decisions. Therefore, the company has requested work to clarify its quality defect costs and to develop a method that can be used to easily continue this work in the future. The study has examined various methods such as production tours, semistructured interviews, and a case study. This was to enable a mapping of quality defects that occur in the company and to analyse and determine which factors are suitable for calculating quality defect costs. After the work, three key factors have been identified as the most important in calculating quality defect costs: administrative work, scrap, and rework. These factors have been used as the basis for creating a general template that can be used by other companies. Organizations that understand the costs that arise from poor quality can utilize this template to improve their financial management. This can create opportunities to make more well-founded and wise investment decisions.