The JEE Main percentile score represents the relative performance of a candidate compared to all other candidates who appeared in the exam session. It indicates the percentage of candidates who scored equal to or less than the candidate. The percentile is calculated separately for each subject and overall. The formula used is: Percentile Score = (Number of candidates with equal or lower score ÷ Total number of candidates in the session) × 100. Percentile scores are used to normalize scores across multiple exam sessions.