The GPA formula
Grade point average is a credit-weighted mean of your course grades. Written out: GPA = Σ(grade points × credits) ÷ Σcredits, where Σ means 'sum of'. Grade points come from a fixed table — 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, D- = 0.7, F = 0.0. Multiply each course's points by its credit hours to get quality points, add the quality points, then divide by the total credits attempted.
Step 1: list every graded course with its credits
Take the transcript or the syllabus and write three columns: course, credits, grade. Include only graded courses — pass/fail, withdrawals and transfer credits without grades carry no grade points and are excluded. Credits matter: a 4-credit course contributes twice as much as a 2-credit one, which is the single most common source of wrong answers.
Step 2: convert each grade to points
Use the scale your school publishes. The standard US 4.0 scale moves in 0.3 steps from 4.0 for an A down to 0.0 for an F, and an A+ usually stays at 4.0. Schools on a weighted scale add a bonus here instead — typically +0.5 for Honors and +1.0 for AP/IB, capped at 5.0. Convert every grade before doing any multiplication; doing both at once is where errors sneak in.
Step 3: multiply points by credits and add
This gives quality points. Worked example — four courses: A (4.0) × 4 credits = 16.0; A- (3.7) × 3 = 11.1; B (3.0) × 4 = 12.0; B+ (3.3) × 3 = 9.9. The quality points total 49.0 over 14 credits.
Step 4: divide by total credits
49.0 ÷ 14 = 3.50. That is the GPA to two decimals. Note what happened: the two A grades did not simply average with the two B grades to give 3.5 by coincidence — the credit hours happened to balance. Change the credits and the same letter grades produce a different GPA, which is the whole reason the weighting exists.
Worked example 2: an unbalanced credit load
Now take a 5-credit B (3.0 × 5 = 15.0), a 3-credit A (4.0 × 3 = 12.0) and a 1-credit A- (3.7 × 1 = 3.7). Quality points = 30.7 over 9 credits, giving 3.41. The simple average of the three grades would be 3.57 — the credit weighting moves the real GPA down by more than a tenth of a point, entirely because the class with the lowest grade carried the most credits.
Unweighted vs weighted in the same transcript
Suppose two of those courses were AP. With a +1.0 bonus, an A becomes 5.0 and a B becomes 4.0 before weighting. The same transcript can then report a weighted GPA well above 4.0 while the unweighted figure stays under it. Both are correct; they answer different questions. The unweighted number compares you against students at other schools, and the weighted number compares you against your school's own ceiling.
What is not included
- Pass/fail courses — credits only, no grade points
- Withdrawals (W) — no grade points and normally no GPA effect
- Transfer credits recorded without grades
- Test credit (AP/IB/CLEP) — usually credits only until a course is graded
- Incompletes (I) — excluded until the final grade replaces them