The formula, a worked transcript, and the mistakes that quietly skew the result
A grade point average is a credit-weighted average, not a plain one. Every course grade becomes a number of grade points, and every course carries as much influence as it carries credit hours:
The weighting is what separates GPA from the simple average of your grades. Two students can hold identical letter grades and still end up 0.2 apart, purely because of which courses those grades were earned in. If the A sits in a one-credit seminar and the C sits in a four-credit lab, the transcript looks better than the GPA does.
1. Pull your full transcript. Write down every course with its credit hours and final grade. Decide up front which entries count — pass/fail courses, transfer credit and repeated courses each follow their own rule, covered further down.
2. Find your school's own grade point table. Your registrar publishes one, usually in the academic catalogue. Use it. Generic tables on the internet disagree about whether A+ is 4.0 or 4.3 and whether an A starts at 90 or 93, and those disagreements are worth 0.1 to 0.3 on a finished GPA.
3. Convert every course individually. Look up each grade separately. Converting your overall average in one lookup produces a different, wrong answer, because the mapping from scores to grade points is a step function rather than a straight line.
4. Multiply out and total. For each course, grade points × credits. Add all of those products; add all the credits.
5. Divide, then round. Total quality points divided by total credits. Round only at this final step, to two decimal places unless your school publishes three.
One semester, five courses, a 4.0 scale where A = 4.0, A− = 3.7, B+ = 3.3, B = 3.0 and C+ = 2.3:
| Course | Credits | Grade | Grade points | Quality points |
|---|---|---|---|---|
| Calculus II | 4 | A | 4.0 | 16.0 |
| General Chemistry | 4 | B+ | 3.3 | 13.2 |
| English Composition | 3 | A− | 3.7 | 11.1 |
| Intro Psychology | 3 | B | 3.0 | 9.0 |
| Public Speaking | 2 | C+ | 2.3 | 4.6 |
| Total | 16 | — | — | 53.9 |
GPA = 53.9 ÷ 16 = 3.37. Notice what the unweighted average would have given: the five grade points average to 3.26. The real GPA is higher because the best grade happens to sit in the heaviest course. That gap is the whole reason credit weighting exists.
A semester GPA uses only that term's courses. A cumulative GPA uses every graded course you have taken. They answer different questions, and the cumulative figure is the one that appears on applications.
The trap is combining them the easy way. Averaging your semester GPAs is wrong unless every semester carried exactly the same number of credits. Go back to the raw ingredients instead: add up all quality points ever earned and divide by all credits ever attempted. A 3.8 earned across 12 credits and a 3.2 earned across 18 credits do not average to 3.5 — they come to 3.44.
These four categories cause most of the confusion, and every institution words them slightly differently. The common patterns:
Three cheap sanity checks catch nearly every arithmetic slip. First, your GPA must land between your lowest and highest course grade points — if you get 3.9 with no A grades, something is wrong. Second, it should sit closer to the grades in your heavy-credit courses than your light ones. Third, recompute total credits independently and confirm it matches the transcript, since a mistyped credit hour is the easiest error to make and the hardest to spot.
When the official number and your own calculation still disagree, the cause is almost always a policy difference rather than arithmetic: a course your school excludes, a retake rule, or a plus/minus grade your table handles differently. Ask the registrar which courses were counted before assuming an error.
GPA = Σ(grade points × credits) ÷ Σcredits. Convert each grade to points on your school's scale, multiply by that course's credit hours to get quality points, total the quality points and divide by total credits.
Each course separately. Converting an overall average once and looking that up in the scale table is the single most common error, and it can be off by 0.2 or more because the conversion is not linear.
Yes, heavily. Credits are the weights in the average, so a B in a four-credit course damages your GPA about twice as much as a B in a two-credit course.
Pass/fail courses normally earn credit but carry no grade points, so they are excluded from the GPA entirely. Transfer credit usually transfers the credits but not the grade points, which means it does not move your GPA at the receiving institution. Check your registrar's policy, because both rules vary.
Two is standard and some schools publish three. Never round in the middle of the calculation; round only the final number, and match whatever your official transcript shows when you report it.