An important part of the U.S. education system is ranking students using a GPA, or Grade Point Average. While it lacks a completely standard calculation formula, the GPA is nevertheless the most accurate way to measure a student's abilities because it accounts for their entire academic career, including the level of difficulty in both the courses and school she attended.

Calculating a Grade Point Average

Generally speaking, a GPA is measured on a zero to four point scale based on the letter grades the student receives: A=4, B=3, C=2, D=1, F=0. These numbers are added together, then divided by the total number of classes. For example, if you receive an A, two B's and a C, add the numbers together (4+3+3+2=12), divide the total number by the number of classes (12/4=3). So the GPA is 3.0. Note that advance Placement (AP) courses may rank as high as a 5.0.

Some schools will include decimal points for pluses and minuses, and other schools will provide a higher number for honors and AP courses. Schools also might ignore certain courses that will not prove useful in academic programs. For example, a law school may not count grades earned in art or music classes, but will rank pre-law courses on a higher scale. This system helps institutions of higher education decide who to accept into their schools, and who has sufficiently completed their work in order to earn a degree.