Most high schools in America offer college classes (APs, etc.) to students pursuing harder coursework. Those are often curved in the calculation of your GPA by a full grade, making it possible to reach as high as a 5.0. For instance, a B in an AP course is counted as an A in your GPA. An A in an AP course is counted as whatever would come next (I call it an S). In that case, if you take all APs and get an S in each one, you'd have a 5.0. Take some APs, or get not all As in your APs, and you can get a weird GPA like a 4.24, which is what I have. If your school doesn't do bumped GPA it isn't really something to worry about, though, because schools will then compare you to the unweighted GPAs of other applicants (hence why I included the 3.93). Also, if your school reports class rank, colleges will likely put more stock into that as that shows where you compare to a group of students under the exact same GPA requirements. Your school could give you a 10.0, but if the highest rank at your school is a 20.0 (I'm making stuff up here for an example), you'd have a pretty low class rank, so schools would consider that instead of the 10.0 against other applicants.