Hey

you cannot convert percentile into marks as percentile is based upon total number of students appearing for the exam. So cannot find out your marks. Your chances of getting in NITs are little. wait for the april session for the final result. You will get the lists after april.

Hello.

The official Jee rankings will be released by NTA after the completion of the April session of the exam. Your predicted rank is about 20670. This rank may change as the best score of the two attempts will be considered for the final rank list. The changes of getting into an NIT are quite slim according to the previous year trends. Refer this link to check the previous year cutoffs:

https://engineering.careers360.com/articles/jee-main-cutoff-for-b-arch-b-planning

Since your percentile score is released relative to the performance of all students attempting the exam, it's quite difficult to predict your exact score. 

Hope this helps.