Letter grades compress a numeric percentage into a category. Scales vary by school, but many US institutions follow a similar breakdown.

Common grading scale

A: 90–100% B: 80–89% C: 70–79% D: 60–69% F: below 60%

Plus and minus

Some schools use A− at 90–92, A at 93–96, and A+ above 97. Always check your syllabus.

FAQ

Is 89.5% an A or a B?
Depends on rounding rules — some teachers round up at .5, others truncate.
Can I use a calculator for this?
Yes — get your percentage first, then map it to your school's scale.