Several schools have charts that convert percentage scores to scaled scores. Since most schools use the standard 4.0 scale, the charts are relatively small and most are similar. Some small differences in the chart may exist from school to school, so be sure you are using your school's specific chart. Using another school's chart may lead to an erroneous conversion since there is no one standard chart for all schools to convert percentages to scaled scores.
Instead of a chart, use brain power to figure out a scaled score. The mathematical equation is: x/20-1= scaled score. In this math equation, x= the percentage score. For example, if the percentage score you want to convert is 80, then divide 80/20 then subtract by 1. So if 80/20 is 4, and 4-1=3, then an 80 percent converts to a 3.0 scaled score. This equation is used when you need to convert a single percentage score into scaled score.
Converting percentages into a GPA scaled score requires some different math. Take all percentage grades and convert them to scaled grades using the equation from Section 2. Write these down on a piece of paper with the number of credit hours for each class. Multiply each scaled score times the number of credit hours for that class and write it down. Add up all these new numbers and divide by the total number of credit hours for all classes. The new number is your GPA.
Colleges have credit hours that are figured into a scaled score, but most other schools don't. If a high school or junior high student wants to figure out his scaled GPA score, he can't use the same equation that a college student uses. Instead, add up the total percentage score of all classes and divide by the number of classes. This new number is the average percentage, which can then be converted to a scaled score either using a school's GPA chart or the equation in Section 2.