There are over 23,500 high schools in the United States, each with its own grading system. While most high schools issue letter grades, some schools use a grading scale based on a point system (for example, out of 100 points). Many schools calculate a weighted grade point average (GPA), while just as many schools don’t. Some schools weight all honors and AP classes, while other schools weight only AP classes.
In addition, many students take courses at multiple schools and colleges during high school, adding another layer of information about coursework and grades that students submit when they apply for college.
With the seemingly infinite ways high schools calculate GPAs, many colleges recalculate the GPA in the application review process to provide a standardized way to compare the academic achievement of students from different high schools. In other words, the GPA reported on your high school transcript is not necessarily what colleges use when reviewing your application.