U.S. colleges, high schools and middle schools all use a percentage scale to assess student performance. Percentages are calculated representing the proportion of correct answers on tests or points on class assignments or homework. Each activity has its own percentage score, and the aggregate semester grade performance is calculated based on points earned vs. total points possible.
A student's grade percentage is then mapped to letter grades and grade points using a table. Every percent fits into a letter grade and GPA range.
Using the common performance definitions for letter grades, the percent scale breaks down in the following manner. The average GPA in high school is 3.0, so scores in the 83% to 86% range indicate you're doing OK. Grades 87% and above demonstrate very good to excellent performance. With scores below 83%, students are dropping below average. Scores below 70% indicate a significant gap in academic achievement and are a cause for concern.
Reference table of the percentage grade scale with letter grade and unweighted GPA point equivalents. This grade scale is used my most U.S. middle schools, high schools and colleges.