Percentage bands
A grading scale maps numerical scores to categories such as A, B, C, D and F. A common example uses 90–100 for A, 80–89 for B, 70–79 for C and 60–69 for D, but many schools use different cutoffs.
Plus and minus grades
Plus/minus systems create narrower bands such as A−, B+ and B. These categories may map to different GPA values. A score of 89.5 could be a B+, A− or A depending on the institution’s thresholds and rounding policy.
Rounding matters
Some instructors round only the final course grade; others round individual assignments; some do not round at all. Never assume that 89.5 automatically becomes 90 unless the syllabus states that rule.
Curves and mastery scales
A curved course may adjust scores using class performance or another formula. Mastery systems may use labels such as Exceeds, Meets or Developing. Those systems cannot be converted reliably to A–F without the official policy.
Find the authoritative scale
Check the syllabus, school handbook or gradebook documentation. If the scale is unclear, ask the instructor before using a generic table to predict a final letter grade.
Boundary scores deserve attention
If your result sits close to a cutoff, such as 89.8 near an A threshold, small policy details matter. Check whether the course rounds, truncates, uses plus/minus bands or calculates from unrounded assignment points. Do not assume the displayed percentage tells the whole story.
Related resources
Reviewed: October 2026. CurioLift explanations are educational; when a school, instructor or required style guide uses different rules, those rules take priority.