The Calculator of Economic Efficiency of Preservation Additives is an interactive web application developed by RIAP (Research Institute for Animal Production) for economic evaluation of investments in biological and chemical preservation additives during ensiling. The software allows users to set operational parameters using sliders (silage feed requirement, ensiled material cost, type and price of preservation additive, expected dry matter losses) and provides comprehensive ROI analysis with graphical visualizations. The application automatically generates recommendations based on economic calculations and includes validation mechanisms for input parameter control. The software builds upon the original additive selection application and together they form a complete decision-making system covering both technical and economic aspects of forage preservation. The application is implemented with offline functionality, requires no installation and is freely accessible to all users.