Hii Meet Sarvaiya,

This is a quite typical question you have asked as the trend and paper pattern of JEE Advanced changes every year. 

But coming to your question:

First let me inform you that JEE Advanced rank depends not only on the marks but also depends a lot on the difficulty of the paper.  So in my opinion one must observe ranks based on the percentage not marks.

For IIT Gandhinagar (Civil engineering) 

in 2018 :

You must have a rank in range of 2320 - 2690. for this rank you can expect a score of 40% to be at the safer zone. which implies that if you score approximate 40% marks in JEE Advanced 2018 then you can get into IIT Gandhinagar Civil, which approximates to 140-150 marks out of 360.

in 2017:

You must have a rank in range of 1680 - 1960. for this rank you can expect a score of 150-160 marks out of 366 to be at the safer zone. which implies that if you score approximate 40% marks in JEE Advanced 2018 then you can get into IIT Gandhinagar Civil.

So, in my view focus on your studies and hope for the best and dont ever check marks for jee advanced because it chnages every year. in an average try to score 40% marks in your exam to meet your said target.

All the best!