Hi Ronak.

To calculate the All India Rank from your achieved percentile, use this formula:

((100-M)/100) * N  +   1.

where M is the Percentile obtained, and N is the number of appeared candidates.

>> Various factors that affect AIR are:

1. Number of students appeared.
2. Difficulty of exam.
3. Performance in exam.
4. Marks obtained in exam.

For simplicity of purpose, you may use this JEE Main college predictor to know your chances into colleges:

Hope this helps. Thanks.