To convert a percentage to a letter grade, you first need to know which cutoff scale applies — because the same 88% can be a B+ under one convention and a B under another. A percentage-to-letter-grade calculator lets you pick the grading convention your school actually uses (a plain 90/80/70/60 scale, a finer plus/minus scale, or an international banding like UK Honours) and instantly matches your score to the correct letter and, for the two letter-grade presets, points under the sample key.
Why the cutoffs matter more than the percentage itself
A percentage tells you a score, but a letter grade requires a cutoff rule. These are the three presets in this tool:
| Convention | A Range | B Range | C Range | Notes |
|---|---|---|---|---|
| Standard (90/80/70/60) | 90-100% | 80-89% | 70-79% | Coarse whole-letter scale, no plus/minus |
| Standard with +/- | 93-100% (A), 90-92% (A-) | 87-89% (B+), 83-86% (B), 80-82% (B-) | 77-79% (C+), 73-76% (C), 70-72% (C-) | More granular; illustrative key; verify locally |
| UK Honours Classification | 70-100% (First) | 60-69% (2:1) | 50-59% (2:2) | Banded classification, not a US-style letter |
An 88% is a B under the plain scale, a B+ under the plus/minus scale, and would fall in the "First" band under UK Honours — three different-looking results from the exact same score, because the boundaries themselves are different.
Step 1: Identify your actual grading convention
Check your syllabus first — most instructors state the grading scale explicitly. If it's not there, check your institution's official academic catalog. Don't assume the standard scale applies by default; some courses, departments, and countries use meaningfully different cutoffs.
Step 2: Locate your percentage on the correct scale
Once you know the convention, find which band your percentage falls into. Most scales use whole-number cutoffs (e.g., 90% and above), so a score like 89.5% typically rounds according to your instructor's stated rounding policy — check whether your school rounds up at the half-point or truncates.
Step 3: Read off the letter grade — and, if needed, its GPA points
Most US conventions also map each letter to an approximate 4.0-scale grade point (A = 4.0, B+ = 3.3, and so on), which is useful if you're feeding the result into a GPA calculation.
Worked example: the same score, three conventions
Suppose you scored 91% on a course.
| Convention | Letter Grade | Approx. GPA Points |
|---|---|---|
| Standard (90/80/70/60) | A | 4.00 |
| Standard with +/- | A- | 3.70 |
| UK Honours Classification | First | Not assigned |
Under the plain scale, 91% clears the 90% cutoff for a straight A. Under the plus/minus scale, 91% falls just short of the 93% cutoff for a full A, landing instead at A- (3.7 points). Under UK Honours, 91% comfortably clears the 70% First-class threshold, but this tool does not assign a US GPA equivalent. A percentage band alone also does not implement programme-specific degree-classification rules.
The UK preset is a simplified band lookup, not a degree-award decision. For example, UCL’s classification rules include final weighted marks and borderline criteria. Consult the applicable programme policy rather than classifying a whole degree from one course mark.
Common situations where the convention trips people up
- Borderline scores near a cutoff. Under the plain preset, 89.4% is B and 90.0% is A — small differences at the boundary matter a lot, so confirm your instructor's exact rounding rule before assuming which side you land on.
- Comparing GPA across schools that use different scales. Two students who both earned "a B" may have scored anywhere from 80% to 86%, depending on which convention their school used — the letter grade alone doesn't tell you the underlying percentage.
- International coursework. If you're converting a foreign transcript, don't assume a US-style cutoff applies. See our guide on converting a foreign transcript to US GPA for how this works when percentages and letter grades don't map cleanly across systems.
- Pass/fail thresholds. Some percentage-to-letter scales set the passing cutoff well below 60% (common in some graduate and professional programs), so don't assume the standard 60% floor for a D or passing grade applies universally.
Try it yourself
Our Percentage to Letter Grade Calculator lets you enter any percentage score and instantly see the matching letter grade under the convention you pick — Standard, Standard with plus/minus, or UK Honours Classification — with sample GPA points for the two letter-grade presets and no GPA equivalence for the UK preset, so you can compare the same score across scales in seconds. Everything is calculated instantly in your browser, with no account required.
