The full conversion chart
- A+ — 97–100% — 4.0 unweighted — 4.5 Honors — 5.0 AP/IB
- A — 93–96% — 4.0 — 4.5 — 5.0
- A- — 90–92% — 3.7 — 4.2 — 4.7
- B+ — 87–89% — 3.3 — 3.8 — 4.3
- B — 83–86% — 3.0 — 3.5 — 4.0
- B- — 80–82% — 2.7 — 3.2 — 3.7
- C+ — 77–79% — 2.3 — 2.8 — 3.3
- C — 73–76% — 2.0 — 2.5 — 3.0
- C- — 70–72% — 1.7 — 2.2 — 2.7
- D+ — 67–69% — 1.3 — 1.8 — 2.3
- D — 63–66% — 1.0 — 1.5 — 2.0
- D- — 60–62% — 0.7 — 1.2 — 1.7
- F — 0–59% — 0.0 — 0.5 — 1.0
Where the boundaries come from
There is no universal authority for the 93% A floor. It is a convention that spread through US school districts, and different districts set it at 90%, 92.5% or 93%. The letter-to-points mapping is far more standardised, which is why transcripts are compared on letters and points rather than percentages. When two schools disagree, it is almost always about the percentage bands, not the points.
Plus and minus grades
Plus and minus grades did not exist in most US schools before the 1990s and still do not exist at some institutions. Where they do, each step is worth 0.3 — enough that a semester of A- grades instead of A grades costs 0.3 GPA points per course. The most common surprise for transfer students is that the receiving school ignores plus and minus entirely and recalculates on whole letters, which can move the GPA in either direction.
Weighted values in the same chart
With the widespread scheme of +0.5 for Honors and +1.0 for AP/IB, the same letter carries more points at higher levels, and the ceiling rises to 5.0. Note that a B in an AP course (4.0 weighted) equals an A in a regular course — the design intent being that rigorous schedules remain competitive. A few schools use 4.3 for A+ unweighted, and a few cap the weighted result at 4.5 rather than 5.0.
Rounding and cut-offs
Most schools round a course percentage to the nearest whole number before applying the band, so 89.5% becomes 90% and an A- rather than a B+. Others truncate, so 89.9% stays a B+. This single policy decision changes letter grades every term for borderline students, and it is worth finding in the syllabus — as is whether a course applies its own higher A floor, which many advanced classes do.
Using the chart
Read left to right to convert a percentage into a letter and its points; read right to left to find what a letter needs. For a full GPA, convert each course first and then apply credit weighting — converting and weighting in one pass is where most hand calculations go wrong.