Last fall, when I was gallivanting around the country during travel season, a few schools were considering switching from weighted to unweighted grade point averages (or the other way around), and asked me what Oberlin would prefer. The answer? We really don't care how your high school calculates GPAs. Here's why:
For every application we receive, the first reader of your application (that's your regional representative--if you go to high school in Louisiana, Alabama, Mississippi, Georgia, Florida, North Carolina, South Carolina, or Arkansas, that's me!) will re-calculate an unweighted four-point GPA, using only your grades in core academic classes.
What's a core academic class? Anything that falls into the category of English, math, science, social studies, or foreign language.
What's not included? Your A's (or C's) in P.E, orchestra, band, typing, art, etc. Also usually not included are journalism and creative writing classes, and anything else that your school might classify as under one of the core academic subjects, but that appears to us to be really "fluffy." We don't count vocational classes (it's cool that you learned how to work on cars/sew garments/fix computers, but we don't count it in your GPA), or anything classified under the vague title of "research" or "independent study" (is this a rigorous academic class? Maybe. Maybe not. Anyway, we're not counting it, unless we know for sure).
Sometimes a class is named something so incomprehensible to outsiders that we have to refer to your school's profile (usually included along with your transcript) or make educated guesses to determine what it really means. That's always fun.
All of this sounds pretty complicated, but we figure out pretty quickly through experience which classes to count and not to count, and it ultimately just involves us typing your grades into a spreadsheet, which spits out a GPA.
As you might imagine, this usually, but not always, results in a number that is quite different from the GPA your high school provides.
What do we do with this number? We record it as part of our written evaluation of your application, along with your GPA for each academic year, so we can see if your grades are trending upwards (good) or downwards (bad).
Recalculating a GPA allows us to have a more consistent number to use in comparing academic records, so we think its utility outweighs the effort required. We will keep your high school GPA as another relevant piece of information, but your recalculated GPA is the main number we use when making decisions, and it's the number we use when reporting the average GPA of our incoming freshman class.
(This is all very important to keep in mind in certain situations, such as when your mom is outraged that her brilliant child with a school GPA of 4.60187xyz was admitted to Oberlin, but did not receive a merit scholarship. Actually, we may have recalculated your core academic GPA to be 3.36--well below last year's average of 3.6--which means we really wish she would stop complaining and be thankful that you were admitted to Oberlin at all.)
Don't forget we also take into account what classes you're taking and what your grades mean in the context of your high school.
This is all the information my application-inundated mind can come up with at the moment, but if you have questions, ask away!