Hello aspirant, your eligibility to apply for IPMAT 2019, clearly depends upon the conversion of your CGPA to Percentage because of the following eligibility criteria:
• If you are from general category or NC-OBC category, you should have scored minimum 60 percent marks in X/ SSC and XII/ HSC or any other equivalent exam.
• But if you are from SC/ ST category or PwD (DA), then minimum percentage is 55 percent to be obtained in class X and XII or SSC and HSC.

So the Percentage of a candidate in their class 10 and 12 will be calculated on the basis of the aggregate marks in all the subjects ( appearing in the marksheet). If in case, the candidates are given grade points or Letter grades by their respective boards instead of marks. Then the conversion of grades into percentage will be done on the basis of the procedure that is certified by the concerned Board.
Therefore, you must check the procedure of the Board from which you got your 10th certificate and marksheet. And convert your grades into percentage.
Furthermore, there are some other eligibility criteria for applying for the entrance exam:
•For general and NC - OBC category: maximum age is 20 years
•For SC/ST and PwD category: maximum age is 25 years.
•Also, being the conducting body of this entrance exam, IIM Indore holds all the rights to change the eligibility criteria in terms of percentage marks, recognition of qualifying exam etc.
• Even the international candidates can apply for this examination if they have cleared their class X and XII from IGCSE (International General Certificate for Secondary Education) board or IB (International Baccalaureate) board.

Please note some important dates for IPMAT 2019. Candidates will be eligible to fill the application form from March 14, 2019 and the last date of submission is April 14, 2019. And the final exam will be conducted on May 10, 2019.
In case you need any further information regarding eligibility criteria, admit card, counselling or even IPMAT 2019, visit the link given below:
https://bschool.careers360.com/exams/ipmat
All the best!
I hope this helps.