Calculating a Semester GPA From Your Course List, Step by Step
Convert each course's letter grade to grade points, multiply by that course's credit hours, sum all the results, then divide by the total credit hours across every course — the credit-hour weighting is what makes this a true GPA calculation rather than a simple average of letter grades.
Working through an actual course list makes the credit-hour weighting concrete in a way the formula alone doesn't quite convey.
The course list
Four courses: a 4-credit course graded A (4.0), a 3-credit course graded B+ (3.3), a 3-credit course graded A- (3.7), and a 1-credit lab graded B (3.0).
The weighted calculation
Grade points × credit hours for each: 4.0 × 4 = 16.0, 3.3 × 3 = 9.9, 3.7 × 3 = 11.1, 3.0 × 1 = 3.0. Summing these: 16.0 + 9.9 + 11.1 + 3.0 = 40.0. Total credit hours: 4 + 3 + 3 + 1 = 11. GPA: 40.0 ÷ 11 = 3.64.
Why this differs from a simple average
A simple, unweighted average of the four letter grades (4.0, 3.3, 3.7, 3.0) would be 3.5 — noticeably different from the correctly weighted 3.64. The gap exists because the 4-credit A carries more weight than the 1-credit B, pulling the true GPA higher than a flat average would suggest.