To calculate your (GPA) Grade Point Average you must first know what your schools grading scale is.
F =0.0
D- =0.7
D =1.0
D+ =1.3
C- =1.7
C =2.0
C+ =2.3
B- =2.7
B =3.0
B+ =3.3
A- =3.7
A =4.0
Straight A's is a 4.0 which requires a student to get all A's or College courses to help bump up anything lower than that to the 4.0 GPA. Some college coursework can allow students to get GPA of 4.5, 5.0, or higher. A+ grades are recognized in some schools but it typically doesn't raise your GPA any higher.
Now once you know what your grades are you take the total of the grade points and divide that by the number of classes you had to get the grade point average (GPA). Some classes are given more weight such is the case in most College courses where you receive more credits. The higher the credits the more the GPA effects the overall grade point average. For example say you had five classes and you received three A's, one B, and one C. You would have a total of 17 GPA points. That would give you a Grade Point Average of 3.4 GPA, which is calculated by taking 17 grade points divided by the number of classes which was 5. In order to make Honor Roll you will need at least a 3.5 GPA. So if you could raise the B and C to a B+ and a C+ and keep the A's you will be able to make Honor Roll with a 3.52 GPA.