Letter Grades Explained: Bands, Points and the Plus/Minus Question
The letter grade is a compression algorithm from the age of paper: squeeze a term's worth of percentages into one symbol a transcript can carry. Like all compression, it loses information — an 83 and an 86 are the same B — and like all compression, it survives because the convenience outweighs the loss. But you cannot manage what you cannot decompress, and most students have never been shown the full table their letters come from.
This article lays the whole system out: where the bands sit, what each letter is worth in grade points, why the plus/minus system exists and who it helps, and the schools that refuse letters altogether.
Key takeaways
- Letters are bands of percentages, not points: on a common scale, A spans 93–100, B 83–86, and so on in a stepped pattern.
- Grade points attach to the letter, not the percentage: A = 4.0, A− = 3.7, B+ = 3.3, stepping by 0.3.
- Plus/minus grading rewards and punishes edge performance inside a band; straight-letter schools widen the bands instead.
- The F is the only letter worth exactly nothing — and its credits still count as attempted, which makes it doubly expensive.
The full band table, read properly
Read the standard table as a rhythm rather than a list. The A− band is 90–92, B+ 87–89, B 83–86, B− 80–82: from the top down, each step costs three or four percentage points and exactly 0.3 grade points. The pattern continues through C and into the D range, where the bands narrow slightly, until below 60 (or 65, in stricter systems) sits the F. A student who internalises the rhythm can locate any percentage in the table mentally, and — more usefully — can see how far their current mark sits from the next band in either direction.
Points attach to the letter, which means the percentage inside the band stops mattering the moment the band is assigned. An 86.4 and an 83.1 are the same 3.0. This flatness inside bands explains a behaviour teachers see every term: effort concentrates ferociously near band edges and relaxes mid-band. It is a rational response to the geometry, and course designers who dislike it change the geometry — by grading on percentages throughout, or by narrowing bands — rather than exhorting students to ignore incentives.
The plus/minus system exists to soften exactly that flatness. Without it, the B band runs a full ten points wide (80–89 in many straight-letter schools) and the difference between its top and bottom is invisible on a transcript. With it, the top of the band earns 3.3 and the bottom 2.7, which tracks real differences in performance more faithfully. Statistically, plus/minus grading slightly lowers average GPAs in practice — the A band gains nothing from its missing A+ on the standard scale, while minus grades pull many students down a step — a trade schools accept in exchange for finer resolution.
Some institutions refuse the compromise and grade on percentages to the end, publishing class averages numerically. Others grade on descriptors, honours classifications, or a 1–7 scale like the IB's. Letters dominate North American transcripts not because they are uniquely just but because they are portable: any registrar can read them at a glance, and any employer can sort by them, which is also their danger — a portable summary invites people to skip the document it summarises.
The F deserves its own paragraph because students misprice it. A fail earns zero points while its credits remain in the attempted column, so a 3-credit F costs what a 3-credit A earns, with interest: pulling a record back up after an F takes roughly two equivalent A's elsewhere. Prevention — dropping a doomed course before the deadline, where policy allows — is worth more than any subsequent heroics, which is why withdrawal dates belong in the same calendar as exam dates.
Borderline policy is the last piece of the system most students never see. Many instructors, faced with an 89.6 in a system where 90 changes the letter, apply a stated rule: round at .5, review participation, or hold the line absolutely. Knowing your instructor's rule is not gaming the system; it is reading it. Syllabi often state it, and office hours exist partly for this question.
None of this machinery is hidden. The bands, the points and the edge rules are published in catalogues and handbooks that students rarely open. An hour with yours — learning where your current marks sit inside their bands — is among the highest-yield reading in your programme, because it converts vague grade anxiety into a set of distances you can actually work on.
What borderline marks teach about effort
There is a strategic lesson hiding in the band table, and students who learn it allocate their final weeks differently. Effort has uneven value across the percentage range: the mark that moves a student from 88 to 90 crosses a band edge and pays 0.4 grade points, while the mark that moves them from 84 to 86 stays inside the B band and pays nothing at all on the transcript — however real the learning was. This is not an argument for valuing only edge-crossing effort; understanding matters beyond its transcript shadow. But when time is scarce and several courses compete for it, the distances to the nearest band edges — above and below — are legitimate planning data, and this site's converters exist so you can read them at a glance instead of guessing which course your next hour is worth most.
A worked example
Priya finishes a course at 89.4 in a plus/minus school: a B+, worth 3.3. Her friend Tom, in a straight-letter school, finishes at 89.4 too: a B, worth 3.0 — because his B band runs 80–89. Their raw performance is identical to the decimal; their transcripts differ by 0.3 grade points on that course, forever. Neither school is wrong. They are answering the resolution question differently, and any reader comparing the two transcripts fairly needs to know it.
Mistakes that cost marks
Treating a letter as a precise score. A B certifies a range of about ten percentage points; admissions and employers who need precision ask for transcripts and class rank, not the letter alone.
Assuming plus/minus helps you. It helps at band tops and hurts at band bottoms; over a degree, students with marks scattered mid-band usually come out slightly behind their straight-letter counterparts.
Ignoring the F's denominator effect. Students plan as if a failed course were merely 'no points', forgetting its credits still divide the average. It is the most expensive letter on the table.
Questions, answered
Why is there no A+ on the standard table? +
Tradition and restraint: the scale's designers capped excellence at 4.0 so the average stayed interpretable. Schools wanting finer resolution at the top bolt on a 4.3 A+, which produces the scale disputes described in conversion guides.
Is a B+ in a hard course better than an A in an easy one? +
On the transcript, the A is worth more points. To a reader who knows the courses — an admissions tutor, a graduate panel — the B+ in the demanding course may say more. Both readings exist; you cannot control which reader you get, so take the hard courses and earn the best letters in them you can.
Do plus/minus grades appear on official transcripts? +
Where the school uses them, yes — they are the official grades, not an internal refinement. That is why the 0.3 steps matter: they are printed, averaged and ranked.
Put it into practice
Look up the letter on your own report and see its band, its points, and what the next band up would have needed.
Open the Letter Grade Converter →