The standard US bands
A common mapping is 93–100 = A, 90–92 = A-, 87–89 = B+, 83–86 = B, 80–82 = B-, and so on down to F below 60.
There is no single official national conversion — each school publishes its own cutoffs, so verify against your catalog.
When you only know marks
If your transcript shows percentages instead of letters, convert each mark to its letter band first, then apply the grade-point scale. Our calculator does this automatically in Marks % mode.