A -> 93-100
B -> 85-92
C -> 77-84
D -> 70-76
E/F -> 0-69http://en.wikipedia.org/wiki/Grading_(education
Chromatic variants ("+" and " − ") are used. In most 100-point grading systems, the letter grade without variants is centered around a value ending in five. The "plus" variant is then assigned the values near the nine digit and the "minus" variant is assigned the values near zero. Any decimal values are usually rounded. Thus, a score of 80 to 82 is a B−, a score 83 to 87 is a B and a score of 87 to 89 is a B+. The four-point GPA scale, the letter grade without variants is assigned to the integer. The "plus" and "minus" variants are then assigned to .3 above the integer and .3 below the integer, respectively. Thus, a B is equal to 3.0, a B+ is equal to 3.3, and a B− is equal to 2.7.
The A range is often treated as a special case. In most American schools, a 4.00 is regarded as perfect and the highest GPA one can achieve. Thus, an A, being the prime grade, achieves the mark of a 4.00; for the A+ mark, most schools still assign a value of 4.00, equivalent to the A mark, to prevent deviation from the standard 4.00 GPA system. However, the A+ mark, then, becomes a mark of distinction that has no impact on the student's GPA. A few schools, however, do assign grade values of 4.33 or 4.30; but the scale is still called "4.0", because grading scales (or "quality indices") take their numerical names from the highest whole number.http://en.wikipedia.org/wiki/Academic_g ... ted_States