Hello.
With your 81.94 percentile in JEE mains January session of exam your approximate all India rank would be calculated through the provided formula:
(100-your percentile score)*869010/100
Here 869010 is a number of candidates appeared for the January session of exam.
So by the treatment of above formula your approximate AIR would be: 156943.
Remember this is your approximate all India rank not your category rank.
So if we compare your rank with the previous year cutoff then you have chances in  NIT Sikkim, NIT Meghalaya, NIT Manipur etc. With home state quota.
Kindly take a view on this previous year cut off list:
https://engineering.careers360.com/articles/nits-cutoff-for-top-btech-branches
Remember this prediction is based on the previous year cutoff list so it might be changed as per the fluctuations.
For more precise predictions of colleges you can go through our college predictor from the provided link:

Best of luck.

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