Convert letter grades to a 4.0 grade point average. A is 4.0, B is 3.0, C is 2.0, D is 1.0 and F is 0. Add or subtract 0.3 for positive and negative letter grades. For example, to find the grade point average of a C-, subtract 0.3 from 2.0. The answer is 1.7.
Use a conversion chart to convert grade point average to a percentage or a letter grade. Conversion charts generally list all three grading scales: GPA, letter and percentage. Find the GPA you wish to change, scan the page to the left and right of the number to convert it into a percentage or letter grade.
Convert scaled point grades to a scaled letter grades. The scale works on a 10-point system, with an extra point given to those receiving an A to make the top possible score an A+. For example, 90 to 100 is an A, 80 to 89 is a B and 70 to 79 is a C. The top and bottom three points of each point grade are either pluses or minuses. For example, 87 is a B+. Depending on the educational institution, 60 to 69 can be a D or 64 and lower can be an F.