Hello dear

I am assuming that your question is in the reference of jee mains. As you cannot calculate your exact rank because it will depends upon various factors which will vary according to the coming exam in July .

But you can use rank predictor which will give you a range of rank you may get assuming all the factors and based on January exam results.

Here you need to put your marks and you will get your percentile  , category rank and general rank.

Good luck