Abstract : The implementation of lean manufacturing practices (LMP) means a systematic approach of several management procedures and practices, which may impact the content, nature and quality of people's work. This implementation process is often performed after an accurate assessment to ensure the effectiveness and e±cient execution of these practices. However, the necessity and logic of different assessments according to the situation required by the assessment objective, the logic requires general rules for designing assessments with effective and reliable results. The aim of this research paper is to develop a logical perception to explain the impact of LMP on the actual and overall performance of the company and explains the computational basics and mathematical equations contributing to the assessment design of these practices to ensure e±ciency and accuracy in the results. Moreover, this study also concludes a novel mathematical equation that can be used in the e®ective assessment to increase the e®ectiveness of evaluation for improvement processes in different sectors