Proper % to GPA conversion (and vice-versa)?

Question

I need to know the proper GPA to percent and percent to GPA conversion.

A Google search reveals:
http://www.cascadia.ctc.edu/Faculty/dwhittaker/percent2gpa.htm

Another website says GPA is Your Aggregate/Highest Aggregate in the Class.

There are 2 different methods of calculation given in the Yahoo Answers.

Wikipedia also has a different conversion.

So now I want to know, which is the right one?

Answer 1

I guess it may vary by school.

I thought it went like this:

percentage letter GPA
90+ A 4.0
80+ B 3.0
70+ C 2.0
60+ D 1.0
below 60 F 0

Many places would give fractional GPA points for getting a plus or minus on a letter grade. Like B+ might be 3.33, but again it probably varies in different schools and different regions.

Answer 2

GPA IS a percentage.