GPA shows up on transcripts, scholarship applications, and grad school requirements — a single number standing in for an entire academic record. The calculation behind it is straightforward once broken down, even though the result can feel opaque.
The core formula
GPA = total quality points ÷ total credit hours. "Quality points" for a single course are calculated by multiplying that course's grade points (on a 4.0 scale) by its credit hours.
Step 1: Convert each letter grade to grade points
Most US institutions use a standard 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, D- = 0.7, F = 0.0. See our guide on converting letter grades to GPA points for the full breakdown, including some institutional variations.
Step 2: Multiply grade points by credit hours
A 3-credit course with a B (3.0 points) earns 9.0 quality points (3.0 × 3). A 4-credit course with an A (4.0 points) earns 16.0 quality points. This step is why credit hours matter so much — see our dedicated guide on why credit hours matter for your GPA.
Step 3: Sum everything and divide
Add up all quality points across every course, then divide by total credit hours (not the number of courses). This weighting by credit hours is what makes GPA a true weighted average rather than a simple average of grades.
A worked example
| Course | Credits | Grade | Points | Quality points |
|---|---|---|---|---|
| Biology | 4 | A | 4.0 | 16.0 |
| History | 3 | B+ | 3.3 | 9.9 |
| Statistics | 3 | B | 3.0 | 9.0 |
| Writing | 2 | A- | 3.7 | 7.4 |
Total quality points: 42.3. Total credits: 12. GPA = 42.3 ÷ 12 = 3.53.
Why a simple average of letter grades gives the wrong answer
Averaging the raw grade points without weighting by credits (4.0 + 3.3 + 3.0 + 3.7 = 14.0 ÷ 4 courses = 3.5) produces a close but technically incorrect result in this example, and the gap grows larger the more credit hours vary between courses. Credit-hour weighting exists precisely because a 4-credit course represents more academic work than a 1-credit course and should count proportionally more.
Cumulative vs. semester GPA
The calculation above works identically whether you're calculating one semester's GPA or your full cumulative GPA — the only difference is which courses (and how many credit hours) go into the sum. See our guide on cumulative GPA vs semester GPA for how these interact.
Skip the manual math
Our free GPA Calculator handles this entire calculation automatically — add your courses, credit hours and grades, and it computes both your term and cumulative GPA instantly.
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