Calculating international GPAs is a bit of a challenge, but we still do give it a shot. There are 4 primary tools that we use when calculating GPAs for school systems with which we are unfamiliar.
First, many, but not all, schools give us a translation system. When they do, we ordinarily use those.
Second, EducationUSA offices in many countries provide a conversion chart and/or can often help us with the effort.
Third, there are professional transcript evaluation firms that we work with. Some schools (especially graduate schools) use these firms to analyze each and every transcript. We don't, but we do use conversion charts that they provide to colleges and universities.
Finally, in rare cases where none of the above work, we use external exam marks, teacher and counselor comments, comparison to class averages, etc. to make a best guess. Because we use a holistic review system, if we're off a few decimal places it doesn't really matter all that much.
In some educational systems exit exams are considered much more important than the coursework that leads to the results. Examples of this are the A-level system in many parts of the world, the WAEC in West Africa, the Cape Exams in the Caribbean, etc. Students studying in one of these systems should know that at Oberlin we place more emphasis on the internal coursework grades than we do on these exit exams. It isn't that we ignore exit exams, but our educational system is much more interested in the process of learning and in developing lifelong learning skills and much less on what you have managed to memorize for an exit exam. Thus we really like to see students who have excelled in the process of learning as assessed by internal marks.