To calculate percentage marks in physics chemistry and Biology you need to get the marks obtained in physics chemistry and Biology and then divide it by the maximum marks of each subjects that is if each paper consists of hundred marks then marks obtained by you out of 300 / 300 x 100 to get the percentage marks.

Dear Jay, to be declared "PASS" in any subject, you should clear both the theory and practical marks. For example, let's say if your Theory marks are for 70 and practicals are for 30 and to be declared pass in Theory you should score 21, you should score a minimum of 21 in Theory and then score the remaining in practicals. Now let's say you scored 21 in Theory and 25 in Practicals, you have passed in the subject. But you the same marks in Biology, Physics and Chemistry you will not be eligible for NEET if you belong to General Category. This is because to be eligible for NEET, you should score a minimum aggregate of 50% in General Category, 45% for PWD and 40% for OBC,SC,ST. In short, including your Theory and Practicals, you should pass the subject and then score the aggregate according to your Category.

Dear Aspirant,

Your complete percentage is calculated after the inclusion of practical marks. You can't calculate your score without your practical marks and you'll be needing a score of complete 100 to find out your percentage. The eligibility is that a candidate must have scored a minimum of 50% marks in Physics, Chemistry and Biology. For GEN-PWD is 45% and for OBC/SC/ST the criteria is 40% in the PCB.

You could check complete eligibility here:

https://medicine.careers360.com/articles/neet-eligibility-criteria

Hope this helps.