Hello Srinithin,

NTA will compare both the percentiles for your January session as well as April session of JEE Mains 2019. According to this the best of two percentile will be considered while making a overall merit list. This overall merit list will be based on your score and your percentile. If two or more people have same score/percentile then different factors will be considered and accordingly the merit list will be declared along with the rank. This percentile system has been adopted to normalise the score and eliminate the gain/loss of marks for easy/hard question paper in different slots.

Hope this answers your question. For further queries comment down below.

Good luck!