Most Helpful Guy
The obvious answer is that it depends on your school's individual dress code.
However, if you want my personal opinion on the matter: Ripped jeans should be allowed as long as they don't violate any of the already existing rules in the dress code. For instance, they shouldn't be ripped high up enough that they are the equivalent of wearing shorts or a skirt that is too short for the dress code's standards. As long as the rips in the jeans don't expose the wrong places, it's fine.
Most Helpful Girl
I think it should be okay, but it does depend on what kind of school you go to and what country you live in to determine if the school thinks it is acceptable I guess.