A percentage in the high eighties or low nineties has no single grade point, because most institutions do not publish a percentage band at all. Where one is published the answer is exact. At the University of Toronto, 85 to 89 per cent is an A and 4.0, and 90 to 100 per cent is an A+ and also 4.0, so an 88, an 89, a 90, a 91 and a 92 all carry four grade points on that scale.
The published band, read straight
Toronto's undergraduate table gives A+ at 90 to 100 per cent, A at 85 to 89, A- at 80 to 84. The grade point column reads 4.0, 4.0 and 3.7. So on that scale an 88 and a 92 are worth the same in grade points and different in letter, which is the kind of detail a general conversion table flattens away.
Why the same figure is unanswerable elsewhere
An institution that publishes only letters and grade points has left the percentage-to-letter step to the instructor. In that setting an 88 in one course and an 88 in another can be different letters, so there is no institution-wide answer to what an 88 is worth. Cincinnati, Xavier and Missouri all publish grade points without bands for exactly that reason.
Getting a defensible answer
For a single course, read the syllabus. For a transcript being sent abroad, read the receiving institution's published conversion. For anything formal, a recognised credential evaluator's statement is the document that will be accepted. Each names an authority, which is the difference between a conversion and a guess.
Questions people ask about what is a 90 gpa
What is 90 per cent as a grade point?
On the University of Toronto's published table, 90 per cent is an A+ and 4.0. At an institution publishing no percentage bands there is no published grade point for a percentage.
Is an 88 the same as a 92?
In grade points on Toronto's scale, yes: both fall in bands worth 4.0. In letters they are not, since 85 to 89 is an A and 90 to 100 is an A+.
Which institutions publish percentage bands?
A minority. In this index Toronto publishes letter, percentage and grade point together; most American registrars publish letters and grade points only.