My parents think that Harvard/other schools recalculate your GPA, assigning ~3.7 for an A- vs 4.0 for an A but I think they treat them the same. I searched this but I couldn’t find any recent and definitive source for this.
Unfortunately, colleges are NOT transparent about this issue and Harvard is no exception. As far as I’m aware, there is no information available about if Harvard recalculates a student’s GPA or how they do it.
There are several articles that address the issue, in general, but it’s safe to say that selective colleges first compare your transcript to those of your peers at your high school by: (a) directly comparing your transcript to other students from your high school that have applied to the same college and (b) by looking through the data supplied on your high school’s profile: https://professionals.collegeboard.org/guidance/counseling/profile/sample
Selective colleges, including Harvard, focus on 5 main academic areas: English, Math, Science, Social Studies and Foreign Language. Other courses such as physical education, drama, theater, music, health, tech classes, shop classes etc are ignored. See: http://greatcollegeadvice.com/calculating-your-real-grade-point-average-gpa/
That’s because there isn’t one. As @gibby said, Harvard won’t tell you. My guess, and it’s only a guess, is that Harvard does not recalculate GPA’s; they take whatever UW GPA is on your transcript. If your HS calculates an A- as a 3.7, then it’s a 3.7. Regardless, an AO can look at a transcript and see that an A is better than an A-.
Sure, you can treat an A- same as A. Why bother fussing over the difference, when they’re admitting holistically, not top down like some public U’s? And who’s got the time?
This is like the fussing over a 740 vs a 750. (MIT has a nice bit that anyone over a certain level is “qualified” to manage the work, once there.) OP should worry abut the rest of the app and supps, making those relevant and worthy.