Why the scale matters
A percentage only becomes a letter grade through a grading scale, and there is no single national scale in the United States. Scales are set by states, districts, schools and sometimes individual departments. The same 84% can be a B on a standard plus/minus scale, a B on a 10-point scale and a C on a 7-point scale. If you teach in a new district, or a student transfers in, the scale is one of the first things to check.
The three common scales side by side
| Grade | Standard (with +/−) | 10-point | 7-point |
|---|---|---|---|
| A | A+ 97–100, A 93–96, A− 90–92 | 90–100 | 93–100 |
| B | B+ 87–89, B 83–86, B− 80–82 | 80–89 | 85–92 |
| C | C+ 77–79, C 73–76, C− 70–72 | 70–79 | 77–84 |
| D | 60–69 | 60–69 | 70–76 |
| F | Below 60 | Below 60 | Below 70 |
Many schools also split D into D+, D and D−. The calculators on this site use the three scales in the table; you can switch between them in the grader settings.
The standard plus/minus scale
This is the scale most people picture when they think of US grades. Each ten-point band is split into thirds: the top three points are the "plus" grade, the middle four are the plain letter and the bottom three are the "minus". The split gives more detail than the 10-point scale. A student at 89% (B+) and one at 80% (B−) both have a B, but the report card shows they are in very different places.
The 10-point scale
The 10-point scale uses the same cut-offs as the standard scale, 90, 80, 70 and 60, but without the plus and minus split. It's easy for students and parents to understand and it's the scale many grade-to-GPA conversions assume. Its weakness is that a 90% and a 100% get the same letter, and a single point at a boundary (89% vs 90%) decides a whole letter grade.
The 7-point scale
A 7-point scale makes each letter grade 7 or 8 points wide and moves the passing line up to 70%. Some districts have used this scale for years; others have moved away from it toward the 10-point scale. It is noticeably stricter:
- An 84% is a B on the 10-point scale but a C on the 7-point scale.
- A 68% passes with a D on the 10-point scale but fails on the 7-point scale.
- A 92% is an A on the 10-point scale but a B on the 7-point scale.
Supporters argue that a higher bar means an A represents stronger work. Critics point out that students on a 7-point scale can end up with lower GPAs than students in a neighboring district who did identical work, which matters for scholarships and college admissions that compare GPAs directly.
The same test on three scales
Take a 25-question test where a student gets 21 correct, which is 84%.
- Standard scale: B (83–86).
- 10-point scale: B (80–89).
- 7-point scale: C (77–84).
Change the scale on the out-of-25 grading chart and you can watch every row change. It's a quick way to show colleagues or parents what a proposed scale change would actually do.
What counts as passing
On the standard and 10-point scales the lowest passing grade is usually a D at 60%; on a 7-point scale it is usually 70%. But "passing" in a course and "passing" for a requirement can differ. Some programs require a C or better for a course to count toward graduation, a prerequisite or transfer credit. If a student needs a specific grade for a reason outside your class, find out early.
How scales connect to GPA
Most US high schools convert final course grades to grade points on a 4.0 scale: A = 4, B = 3, C = 2, D = 1, F = 0. With plus and minus grades, a common version is A− = 3.7, B+ = 3.3, B− = 2.7 and so on, though schools differ on whether an A+ counts as 4.0 or 4.3. Honors and AP courses may add an extra point on a "weighted GPA". Because these conversions vary, always use your school's official table when a GPA matters.
Quick answers
Is 84% a B or a C?
It's a B on both the standard plus/minus scale and the 10-point scale, and a C on a 7-point scale.
What is the most common grading scale in the US?
The standard scale with 90/80/70/60 cut-offs, either with plus and minus grades or as a plain 10-point scale, is the most widely used. Some districts use a stricter 7-point scale.
This guide explains common practice and the math behind it. Grading rules differ between schools, so always check your school or district policy. Spotted an error? Let us know and we'll fix it.