A 3.8 on a 4.0 scale, an 92 on a 100-point scale, and a 38 predicted IB score aren't the same measurement, and no formula converts perfectly between them -- which is exactly the problem colleges receiving applications from thousands of different high schools have to solve every year. There's no single industry-standard answer for how they solve it. Three real, documented examples show how differently colleges actually handle this: the University of California runs every applicant's transcript through a published weighted formula, the University of Michigan converts everything to a simpler unweighted 4.0 scale, and Wellesley has said outright that it doesn't spend much time on a recalculated number at all -- it reads the transcript line by line instead.
Why raw GPAs aren't comparable in the first place
High schools don't agree on a single grading system. Some report on a straight 4.0 scale, some use 100-point percentage scales, some use a 4.3 or 4.5 scale that gives an A+ extra value, and international and IB-affiliated schools often report neither -- IB itself scores on a 1-7 per-subject scale (7 being highest) rather than anything resembling a GPA. Layer weighting on top of that: one school might add a full point for every AP class, another adds half a point, another doesn't weight coursework at all, and a growing number of schools use standards-based or mastery grading that doesn't produce a traditional GPA in the first place, covered in our piece on unweighted vs. weighted GPA. A "4.6" from one school and a "4.6" from another can represent genuinely different levels of achievement -- which is exactly why admissions offices don't take the number on your transcript at face value.
The school profile does the translation work
Every high school's transcript is accompanied by a school profile -- a document the counseling office sends alongside your application that explains the school's specific grading scale, weighting policy, course offerings, and how GPA and (if reported) class rank are calculated locally. It's the context an admissions reader uses to interpret your number correctly, whether or not the college also runs its own recalculation on top of it.
Three real approaches, side by side
University of California publishes its formula outright: it recalculates using only UC-approved "a-g" courses completed between the summer after 9th grade and the summer after 11th grade (freshman and senior grades don't count), converts letter grades on a straightforward A=4/B=3/C=2/D=1 scale with pluses and minuses ignored, then adds one bonus point per semester of honors-level, AP, IB, or transferable college coursework, capped at a maximum of 8 semesters of bonus points. It's a fully weighted, published, rule-based conversion -- the most formal version of GPA recalculation in wide use.
University of Michigan takes a simpler route: it converts every applicant's 9th-through-11th-grade coursework to an unweighted 4.0 scale, again ignoring pluses and minuses, and does not add points for AP, IB, or honors courses at all. Course rigor still matters to Michigan's decision -- it's just evaluated as a separate factor in holistic review, not folded into the GPA number itself.
Wellesley College, at the other end of the spectrum, has described spending comparatively little time on a recalculated GPA figure at all, instead reading each applicant's actual transcript line by line in context. For schools that review this way, no universal formula exists to publish, because the number itself isn't the primary tool -- the transcript, read against the school profile, is.
Three highly selective schools, three different methods -- and none of them is "the" way colleges calculate GPA, because there isn't one.
International and percentage-scale transcripts
For schools reporting on a 100-point percentage scale or a non-U.S. system, colleges generally rely on the same tools rather than inventing something new: the school profile's explanation of the local scale, and — particularly for the IB Diploma Programme — reading the reported IB score (out of 45, or the individual 1-7 subject scores) directly rather than forcing it into a U.S.-style GPA equivalent. IB and other rigorous non-U.S. curricula are read as their own signal of rigor, not converted into a number that would lose the context a direct reading provides.
What this means for you
- Don't assume your school's specific scale or weighting system puts you at a disadvantage. The school profile exists specifically so readers interpret your number in context, not against a school with a different formula.
- Don't try to reverse-engineer a specific college's exact recalculation formula and optimize for it, unless that college (like UC) has actually published one. Most selective private colleges haven't, and chasing a number that isn't the actual evaluation tool wastes effort better spent on course selection and grades themselves.
- Course rigor is evaluated one way or another, even at schools that don't fold it into the GPA number. Michigan's unweighted recalculation doesn't mean AP and honors classes go unnoticed -- rigor still factors into holistic review separately.
- The clearest signal across every method here is the same one: strong grades in the most rigorous schedule your school actually offers reads well whether a college recalculates with a formula, an unweighted conversion, or no conversion at all.