How GPA Is Calculated: Weighted, Unweighted and the 4.0 Scale

One formula underneath every GPA

A GPA looks like a school secret, guarded by registrars and transcript software. It isn't. It's a weighted average — the same arithmetic as a shopping basket where some items cost more than others. Each course contributes grade points multiplied by its credit hours. Add those products up, divide by the total credit hours, and you have the GPA.

GPA = (sum of grade points × credits) / (total credits).

That's genuinely all of it. Every complication people argue about — weighted scales, cumulative totals, plus and minus grades — is a variation on what number goes into "grade points" or which courses get counted. The division itself never changes.

The 4.0 scale: turning letters into points

Before you can average grades, you have to turn letters into numbers. The standard unweighted US scale, the one the calculator below uses, runs like this:

Two details in that table surprise people. First, an A+ usually earns no more than an A — the scale caps at 4.0, so the plus is an honour, not a bonus. Second, an F isn't a small score, it's a zero, and it still counts its credits in the denominator. One F in a 3-credit course doesn't just fail to help; it actively drags, which is why a single bad course can dent a transcript out of proportion to its size.

Not every school prints this exact table. Some don't use plus/minus steps at all, so a B is a B whether it was nearly an A or nearly a C. Check your own school's scale before you calculate — the formula is universal, the point values aren't quite.

A worked example, credits and all

Take three courses, the example used by the calculator below: an A in a 3-credit course, a B+ in a 4-credit course, and a C in a 3-credit course.

Convert each letter: A = 4.0, B+ = 3.3, C = 2.0. Multiply by credits: 4.0 × 3 = 12, 3.3 × 4 = 13.2, 2.0 × 3 = 6. Add them: 31.2 grade points. Total credits: 3 + 4 + 3 = 10. Divide: 31.2 / 10 = 3.12. That's the GPA.

Notice what the credits did. The B+ contributed more points than the A did, because it sat in a heavier course. If you'd averaged the three letters naively — (4.0 + 3.3 + 2.0) / 3 = 3.10 — you'd get a close but wrong answer, and the gap grows as credit loads get less even. A 1-credit lab and a 4-credit lecture are not equal citizens in this average, and they were never meant to be.

Calculate your own, step by step

1. List every graded course for the term, with its credit hours. Leave out pass/fail courses for now — most schools exclude them from GPA entirely, though the pass still counts toward your degree.
2. Convert each letter grade to points on your school's scale. Use the table above if your school follows the standard 4.0 scale.
3. Multiply each course's points by its credits, and add those products into one total.
4. Add up the credit hours of the same courses.
5. Divide total grade points by total credits. Round the way your school does — most report two decimal places — and that's the term GPA.

Want to test a what-if? That's the same list with one letter swapped. It's a healthy use of the calculator below: change the grade you're still studying for, in the course with the most credits, and you'll see exactly where an extra push moves the number most.

Weighted GPA: when an A is worth 5.0

Everything above is the unweighted scale, where 4.0 is the ceiling for everyone. Many US high schools also publish a weighted GPA that pays a bonus for harder courses. The common pattern — and it is only a pattern, not a national rule — adds about half a point for honours courses and a full point for Advanced Placement (AP) or International Baccalaureate courses. On that scale an A in an AP course can be worth 5.0, an A in an honours course 4.5, and a transcript can top out above 4.0.

Why do both numbers exist? Because they answer different questions. The unweighted GPA asks how well you did, full stop. The weighted one asks how well you did given how hard a schedule you chose. Neither is "the real one" — which is why many colleges recalculate applicants' GPAs on a common scale. A 4.6 weighted and a 3.9 unweighted can be the same student, the same grades. If an application asks for your GPA, report the version they ask for, and say which scale it is.

Cumulative GPA: semesters have weights too

A cumulative GPA is the same formula stretched over your whole programme: every graded course, every credit, one big weighted average. The useful shortcut is to treat each finished semester as if it were a single course — its GPA is the "grade", its credit total is the "weight".

Why not just average the semester GPAs? Because semesters carry different loads. Say semester one was 12 credits at a 3.8 GPA (12 × 3.8 = 45.6 points) and semester two was 18 credits at 3.0 (18 × 3.0 = 54). Averaging the two GPAs directly gives (3.8 + 3.0) / 2 = 3.4. The real cumulative figure is (45.6 + 54) / 30 = 3.32. The lighter, shinier semester was pulling the simple average up beyond what the credits justify.

This explains a feeling every student knows. Early on, each semester swings the cumulative number hard, because the denominator is small. Later, the same semester barely moves it — a senior's cumulative GPA is a ship with a lot of momentum. One rough term gets diluted as more credits pile up.

A few policies vary enough that no guide can settle them: whether a repeated course replaces the old grade or averages with it, whether transfer credits bring their grades with them (often they count for credit but not for GPA), and how withdrawals are recorded. Those are your school's rules, printed in its catalogue — read them there before you plan around them.