Plus/minus grading adds intermediate grade values — like A-, B+, and C- — between the whole letter grades, typically worth ±0.3 or ±0.33 grade points, which means your GPA can end up either higher or lower than it would under straight-letter grading, depending on whether your scores tend to land on the "plus" or "minus" side of each grade band.
What is plus/minus grading?
Straight-letter grading uses only five values: A, B, C, D, F, each worth a whole number of grade points (4, 3, 2, 1, 0). Plus/minus grading subdivides each of those bands further — so instead of a flat "B" covering, say, 80–89%, you get B-, B, and B+ covering narrower ranges, each with its own grade point value.
This gives instructors more precision in reflecting where exactly in a grade band a student's performance fell, but it also means the same raw percentage score can produce a different GPA contribution depending on whether your school uses plus/minus grading or not.
Plus/minus grading became widespread across US colleges gradually, and adoption still isn't universal today — some institutions rolled it out decades ago, others still use straight letters, and a few have switched back after adopting it, usually citing student pushback over how narrow the grade bands feel. If you're comparing GPAs between two schools, it's worth checking which system each one uses before assuming the numbers mean the same thing.
Straight-letter vs. plus/minus comparison table
| Percentage Range | Straight Letter | Straight GPA | Plus/Minus Letter | Plus/Minus GPA |
|---|---|---|---|---|
| 97–100 | A | 4.0 | A+ | 4.0 |
| 93–96 | A | 4.0 | A | 4.0 |
| 90–92 | A | 4.0 | A- | 3.7 |
| 87–89 | B | 3.0 | B+ | 3.3 |
| 83–86 | B | 3.0 | B | 3.0 |
| 80–82 | B | 3.0 | B- | 2.7 |
| 77–79 | C | 2.0 | C+ | 2.3 |
| 73–76 | C | 2.0 | C | 2.0 |
| 70–72 | C | 2.0 | C- | 1.7 |
| Below 70 | D / F | 1.0 / 0.0 | D+ / D / D- / F | 1.3 / 1.0 / 0.7 / 0.0 |
Notice that a 90% earns a full 4.0 under straight-letter grading but only 3.7 under plus/minus grading — while an 86% earns exactly 3.0 under both systems, since it sits in the middle of the B band rather than near an edge. The pattern holds across every band: scores near the top or bottom edge of a range are where plus/minus grading changes the outcome, while scores near the middle are unaffected either way.
Worked example: The same grades under both systems
Consider one student's semester, with percentage scores that happen to cluster near the top of each grade band:
| Course | Credits | Percentage |
|---|---|---|
| Biology | 4 | 91% |
| English | 3 | 88% |
| Algebra II | 3 | 82% |
| World History | 3 | 96% |
Straight-letter GPA
| Course | Letter | GPA Points | Quality Points |
|---|---|---|---|
| Biology | A | 4.0 | 16.0 |
| English | B | 3.0 | 9.0 |
| Algebra II | B | 3.0 | 9.0 |
| World History | A | 4.0 | 12.0 |
Total credits: 4 + 3 + 3 + 3 = 13
Total quality points: 16.0 + 9.0 + 9.0 + 12.0 = 46.0
Straight-letter GPA = 46.0 ÷ 13 = 3.54
Plus/minus GPA
| Course | Letter | GPA Points | Quality Points |
|---|---|---|---|
| Biology | A- | 3.7 | 14.8 |
| English | B+ | 3.3 | 9.9 |
| Algebra II | B- | 2.7 | 8.1 |
| World History | A | 4.0 | 12.0 |
Total quality points: 14.8 + 9.9 + 8.1 + 12.0 = 44.8
Plus/minus GPA = 44.8 ÷ 13 = 3.45
For this particular student, plus/minus grading lowered their GPA by 0.09 compared to straight-letter grading — because three of their four scores (91%, 88%, and 82%) fell near the lower edge of a grade band rather than the middle or top. A student whose scores clustered near the top of each band (say, 95%, 89%, and 86%) would see the opposite effect, with plus/minus grading raising their GPA instead. You can test your own grades under both systems using our GPA Calculator.
Why this matters for students
- Comparing GPAs across schools: A 3.5 GPA from a straight-letter school and a 3.5 GPA from a plus/minus school don't necessarily reflect identical academic performance, since the underlying scoring precision differs.
- Borderline percentage scores: Under plus/minus grading, a single percentage point near a cutoff (like 89% vs. 90%) has a real, quantifiable GPA impact — under straight-letter grading, that same point often makes no difference at all, since both fall in the same "B" band.
- Motivation effects: Some institutions adopt plus/minus grading specifically to reduce the incentive to stop trying once a student has "locked in" the top of a letter grade band, since a 90% and a 99% are no longer worth the same thing.
Common edge cases
- No A+ above 4.0: Some schools include A+ in their plus/minus scale but still cap it at 4.0 rather than awarding 4.3, so it functions more as recognition than as an actual GPA boost.
- No F+/F- distinction: Nearly all plus/minus scales still treat any failing score as a flat F worth 0.0, without further subdivision.
- Inconsistent increments: Some schools use ±0.3 for plus/minus increments; others use ±0.33 or round differently — small differences that compound across a full transcript.
Try it yourself
Not sure how plus/minus grading affects your own GPA? Enter your actual percentage or letter grades into our GPA Calculator and see the credit-weighted result instantly — calculated privately in your browser, with no account required.
