This paper presents the teachers’ perceptions of the Letter Grading System (LGS) at secondary-level schools in the Tarakeshwor Municipality of Kathmandu district. The main objective is to study teachers’ perceptions of LGS and identify how to address its foremost challenges. This research is based on phenomenological design and prefers citizen constructivism. Data is collected using decisive sampling methods and a semi-structured interview tool. The teachers’ practices with the LGS are significant, appropriate, motivated, and suitable for stimulating the Nepali education system. Similarly, undergraduates’ and their parents’ perceptions are simply ensuing generous promotion strategy with advancement to their child without difficulties. As a result, there is a mismatch between the evaluation technique’s practices and teachers’ perceptions of the LGS for tracking students’ progress. Furthermore, as discussed in this article, the LGS has assessed the student’s proficiency and rational domain using nine reformist scales based on the performance opportunity provided. Finally, an experienced teacher believes that LGS has biased, liable, productive, and merit-based assessment tools in education without incorporating non-standardised tests into the school assessment system. Currently, LGS has a far better assessment method in the school appraisal system if it is possible to integrate non-testing devices, such as project work, classroom assignments, homework, group work, practical work, etc., as an assignment.