how to calculate Mark's into percentile.

Hello,

Marks and Percentile are apparently not related to each other. Your percentage depends on your marks. But your percentile totally depends on your rank and number of students.

A percentile is a measure used in statistics indicating the value below which a given percentage of observations in a group of observations falls.

Suppose there are total 100 students. Consider your rank is 40th among the 100 students. This means that 60% students are below you or you are above 60% of the students. So, your percentile will be 60 percentile. Now, it doesn't matters that how many marks you have. The only thing that will affect your percentile is your rank.

Best Wishes.