Scholarships, grad school and internships all ask for your GPA. Enter each course with its letter grade and credit hours to get a weighted GPA — the version where a 4-credit course moves your average three times as much as a 1-credit seminar, because it should.
The formula
GPA = Σ(grade points × credits) ÷ Σ(credits). Grade points on the standard 4.0 scale: A = 4.0, A− = 3.7, B+ = 3.3, B = 3.0, B− = 2.7, C+ = 2.3, C = 2.0, C− = 1.7, D+ = 1.3, D = 1.0, F = 0. Example: an A in a 4-credit course and a B in a 3-credit course give (4.0×4 + 3.0×3) ÷ 7 ≈ 3.57.
Weighted vs unweighted
Unweighted average treats every course equally — a 1-credit PE class moves it as much as a 4-credit calculus class. GPA weights by credits, which is why your hardest courses dominate it. Some high schools also add weighted GPAs for AP/IB courses (up to 5.0) — colleges usually recalculate to their own scale, so check their method.