Dear Student,
For checking your chances of admissions you need to check out your normalised score based on your 12th percentage. For even being eligible for any NIT you need to have a minimum of 75% in your 12th. Other than that your rank will be taken of your normalised score, for securing a seat in any of the NIT's you need to have a rank under 2500 to maximum 3000 if with any quota.
Hope this might help you.