My HS is not competitive and my class rank is about 150/650 at a 3.75 UW GPA because of my course load (5 AP, 2 Honor, 1 Normal). I know for dang sure that most of the students above me have an easy course load giving them a 4.0 or anything better than mine. Only about 15 other students have the same course rigor as me. Talked to GC and she said if our school weighted I’d be in that top 5%. Of course, I won’t be able to use that on CommonApp. Will putting my unweighted stats hurt my chance of admissions to schools that want you in the top 10%-20%? Thanks 
Colleges will see your rank, for sure, but they will also see your course schedule and read the school report, in which I’m sure your GC will mention that rank is calculated based on UW GPA. I doubt it will negatively affect you, based on the fact that you have a rigorous course load and clearly a strong academic record.
@yonceonhismouth Thanks for this. I was actually typing a bump as I got the notification lol.
Should I put the rank calculation in the additional details tab on CommonApp? Our GC is scattered where one manages about 250 at our school.
Yea, you could, but the school report is sent by GCs to every college- same information for every student, its just about how the school operates and what they offer, so information about how rank is calculated would be there.