Obtain your college grades. You can do this by requesting a copy of your transcripts from your college or university. Your transcripts state your grades throughout your college career.
Give numeric value to each of your letter grades. The LSAC uses a specialized GPA scoring system that values grades based on three parts. Rather than having an "A" in a class and receiving four points for it, as you would for most GPA calculations, your numeric value is based on the type of "A" you have: A+, A or A-. Your "A+" is worth 4.33 points, your "A" is worth 4.0 points and your "A-" is worth 3.67 points. Each letter grade drops by .3 points.
Add together the point values of each grade and divide them into the number of credit hours each class you took was worth. If you took 3 classes worth 3 credit hours each this semester and you have grades A+, B- and A-, your grades are worth 10.67 points. Divide that into 15 credit hours to come up with a GPA of 3.56.