Step one: percentage to letter
Your teacher or school sets the cutoffs. A few that are published:
- North Carolina's state scale, as shown on an Onslow County Schools page, is A for 90 to 100, B for 80 to 89, C for 70 to 79, D for 60 to 69 and F for 59 and below. There are no pluses or minuses.
- Green Bay's public schools start an A at 93, an A- at 90, B+ at 87, B at 83, B- at 80, and continue in steps of three or four down to D- at 60.
- Alexandria City High School in Virginia uses the same breakpoints from A to C-, and has D+ at 67 to 69 and a D from 60 to 66.
- Forest Hills in Ohio has an A+ at 97 to 100, an A at 93 to 96, and treats anything below 65 as an F.
- Broward County, Florida splits its B and C bands with a plus (87 to 89 for B+) but gives the plus no extra points in its state GPA.
Before 2015, North Carolina used a 7-point scale where an A started at 93, a B at 85 and a C at 77. The state moved to the 10-point scale and the change was described as a way to level the field for college applicants. The University of Georgia's admissions blog lists 10-point scales, 7-point scales and plus/minus grading among the many systems it sees, which is one reason it recalculates.
The College Board's chart is only an example. It says an A runs from 90 to 100, a B from 80 to 89, a C from 70 to 79, a D from 66 to 69 and anything below 65 is failing, and it adds that schools use different cutoffs. Read it as a rough picture, not a rule. (It leaves 65 unassigned, which tells you how much to lean on it.)
Step two: letter to points
Once you have the letter, the points come from the scale. The plain scale gives A 4, B 3, C 2, D 1, F 0. Plus/minus scales give A- 3.7, B+ 3.3, and so on, with a few variations:
- A+ is 4.0 on several registrar tables and 4.3 at Cornell's ILR college.
- Some schools use thirds (3.67, 3.33).
- The University of California ignores pluses and minuses for its admission GPA.
The high school GPA calculator lets you choose any of these scales.
The same percentages on three scales
Here is how ten percentages convert on three published scales. The first column is North Carolina's whole-letter scale, the second is Alexandria City High School's plus/minus letters on the 3.7 scale, and the third is Green Bay's plus/minus with thirds.
| Percent | NC whole letters | Alexandria plus/minus | Green Bay thirds |
|---|---|---|---|
| 95 | A, 4.0 | A, 4.0 | A, 4.0 |
| 91 | A, 4.0 | A-, 3.7 | A-, 3.67 |
| 89 | B, 3.0 | B+, 3.3 | B+, 3.33 |
| 86 | B, 3.0 | B, 3.0 | B, 3.0 |
| 82 | B, 3.0 | B-, 2.7 | B-, 2.67 |
| 78 | C, 2.0 | C+, 2.3 | C+, 2.33 |
| 74 | C, 2.0 | C, 2.0 | C, 2.0 |
| 71 | C, 2.0 | C-, 1.7 | C-, 1.67 |
| 68 | D, 1.0 | D+, 1.3 | D+, 1.33 |
| 64 | D, 1.0 | D, 1.0 | D, 1.0 |
Look at the 91. It is a 4.0 in one place and a 3.7 in two others, and it is the same piece of work. Look at the 82 as well. A whole-letter school calls it a B at 3.0, and the plus/minus schools drop it to 2.7.
On a whole-letter scale an 80 and an 89 are both 3.0. On a plus/minus scale the steps are smaller, so each point near a cutoff matters a little more.
Convert first, then average
The standard order is to convert each course to points and then average, not to average the percentages first.
Take three courses at 91, 79 and 88. On the Green Bay percentage bands with the 3.7 point values, they are A- (3.7), C+ (2.3) and B+ (3.3). The total is 9.3, and 9.3 divided by 3 is 3.10.
If you average the percentages first, you get (91 + 79 + 88) / 3 = 86, which falls in the B band (3.0). The route you take changes the answer by 0.1, and in other cases the gap can be larger. Schools convert at the course level, because the course grade is the record.
Rounding
A percentage can land between cutoffs. If a teacher rounds 89.6 up to 90, it becomes an A- or an A. Whether it does is the teacher's rule, and no source we read gives a standard. Ask early in the term, not after final grades.
Which conversion do colleges use?
Some colleges work from letter grades rather than your school's percentages. UGA says it converts each grade according to the grading scale in use at your high school and puts it on a standard 4.0 scale. UC uses A=4, B=3, C=2, D=1 and says pluses and minuses do not count. That is why the boundary between a B+ and an A- can matter more than it seems: on a plus/minus transcript it moves a grade across a whole letter in a plain 4.0 calculation, even though the percentage difference is a point or two.
Use the calculators on this site to try both versions. Then check your school's published scale, since that is the one that built your transcript.