Your GPA is a credit-weighted average of your grades. The weighting part matters: a 4-credit lab moves your GPA more than a 1-credit seminar, because it counts more. Once you understand that, the formula itself is simple arithmetic.
This guide walks through the formula, a worked semester example, and how cumulative GPA differs. Every number below has been checked.
What is the GPA formula?
The key idea is quality points. For each course, multiply its grade points by its credit hours. An A is worth 4.0 grade points, a B+ is 3.3, a B is 3.0, and so on down your school's scale. Multiplying grade points by credits gives that course's quality points: its contribution to the numerator.
Add up the quality points from every course, then divide by the total credits. That single division is your GPA. Courses worth more credits carry more weight automatically, which is exactly what the credit-weighting is supposed to do.
Worked example: calculating a semester GPA
Say your semester has three courses. Biology, 3 credits, where you earned a B+ worth 3.3 grade points. English, 3 credits, with an A− worth 3.7. Calculus, 4 credits, with a B worth 3.0.
First, compute each course's quality points:
Biology: 3.3 × 3 = 9.9 quality points. English: 3.7 × 3 = 11.1 quality points. Calculus: 3.0 × 4 = 12.0 quality points.
Then add them: 9.9 + 11.1 + 12.0 = 33.0 quality points across 10 total credits. GPA = 33.0 ÷ 10 = 3.30.
Try your own courses in the GPA Calculator, which runs this exact arithmetic for you.
How is cumulative GPA calculated?
Cumulative GPA is still quality points divided by credits, but across every completed semester, not just one. This is where most mistakes happen: cumulative GPA is NOT a plain average of your semester GPAs.
A plain average would ignore that semesters carry different credit loads. Consider this worked example. You have banked 60 credits at a 3.20 GPA, which is 60 × 3.20 = 192.0 quality points. Then you complete a 15-credit semester at a 3.60 GPA, which is 15 × 3.60 = 54.0 quality points.
Total quality points = 192.0 + 54.0 = 246.0. Total credits = 60 + 15 = 75. Cumulative GPA = 246 ÷ 75 = 3.28.
A plain average of 3.20 and 3.60 would wrongly say 3.40. The credit-weighted answer, 3.28, is correct because the 60-credit history outweighs the 15-credit semester.
Why does cumulative GPA move so slowly?
Because your banked credits dilute each new semester. Early on, a great semester can swing your GPA visibly. Later, each semester is a smaller slice of a larger total.
Say you have banked 60 credits at a 4.0 GPA, which is 240 quality points. Now you take one 3-credit course and earn a B worth 3.0 grade points: 3.0 × 3 = 9 quality points.
New cumulative GPA = (240 + 9) ÷ (60 + 3) = 249 ÷ 63 ≈ 3.95. One B cost only five hundredths off a perfect record, because 63 credits of history absorbed it. The more credits you have banked, the slower any single semester can move the needle in either direction.
Edge cases: F grades, withdrawals, and pass/fail
Not every mark on a transcript counts the same way. The rules below are the standard treatment at most schools, but your registrar's policy is the final word.
F grades count, harshly. An F is 0.0 grade points, and unlike a withdrawal, its credits stay in the divisor. So a 3-credit F adds nothing to the numerator while adding 3 to the denominator, dragging the GPA down.
Withdrawals (W) are excluded entirely. A standard W appears on the transcript but contributes no grade points and no credits to either side of the division. It does not move your GPA.
Incompletes (I) are excluded until resolved. An I is not part of the math while it is pending. If it is never resolved, many schools convert it to an F, at which point the 0.0-and-credits-count rule above applies.
Pass/fail courses are excluded from both sides. A pass or fail grade carries no grade points and its credits do not enter the numerator or the divisor. It has no effect on your GPA either way.
Repeated courses are school-dependent. Some schools replace the old grade with the new one, some average both attempts, and some keep both on the transcript while counting only one. Check your registrar before assuming how a retake will count.
Practice with your own numbers
The formula is always the same: quality points divided by credits, weighted by credits. Semester GPA applies it to one term, cumulative GPA applies it to everything you have completed, and credit loads decide how much each piece matters.
Enter your own courses and credits into the GPA Calculator to get your result instantly, or use the Grade Conversion Calculator if you need to convert grades between different scales first.