10 min read
A letter is a band, not a single percent
On our US Standard table, B is 83–86% and B+ is 87–89%. The letter-grade calculator shows the midpoint of that band so you can plug a letter into a weighted average when the teacher never published a percent.
Plus and minus matter
A− (3.7) versus A (4.0) is 0.3 GPA points. Over a 3-credit course that is 0.9 quality points — enough to change a 3.48 into a 3.51 at the margin. Do not ignore the minus.
Convert both directions
Percentage → letter answers “what did I earn?” Letter → percentage answers “what number should I use in a weighted average?” Use both converters with the same scale selected.
International letters are not US letters
A UK 60% is often a 2:1, not a US D. An Australian HD is closer to a US A. Always switch the scale before you convert.
GCSE 9–1 is another letter system
England’s GCSE 9 is higher than 8, and 4 is a standard pass. That is not a US A–F table. Use the GCSE calculator for those percentages, not the US letter converter.
Why teachers publish midpoints
When a rubric only shows letters, a weighted average still needs a number. The midpoint of the band (B+ ≈ 88% on US Standard) is the honest default until the teacher posts a percent.