How to calculate your GPA
GPA is a single number that compresses an entire transcript into something admissions offices, scholarships, and employers can compare at a glance. Understanding how it is built — and exactly where the math comes from — takes the mystery out of it and tells you which grades actually move the number.
The grade-point scale
Most U.S. high schools and colleges use a 4.0 scale where letter grades map to numeric grade points. The standard mapping looks like this:
| Letter grade | Typical percentage range | Grade points (unweighted) |
|---|---|---|
| A+ | 97–100 | 4.0 |
| A | 93–96 | 4.0 |
| A− | 90–92 | 3.7 |
| B+ | 87–89 | 3.3 |
| B | 83–86 | 3.0 |
| B− | 80–82 | 2.7 |
| C+ | 77–79 | 2.3 |
| C | 73–76 | 2.0 |
| C− | 70–72 | 1.7 |
| D | 60–69 | 1.0 |
| F | 0–59 | 0.0 |
These are the most common values, but some schools use a simpler scale without plus/minus grades (A = 4.0, B = 3.0, C = 2.0, D = 1.0, F = 0.0), and some use different cutoffs for the percentage ranges. The right scale is the one in your course catalog or transcript guide — not a general table found online.
Unweighted GPA: the basic calculation
An unweighted GPA treats every class the same regardless of difficulty level. The formula is:
Unweighted GPA = (sum of all grade points) ÷ (number of classes)
Suppose you take five classes in a semester and earn these grades:
| Class | Grade | Grade points |
|---|---|---|
| English | A− | 3.7 |
| Algebra II | B+ | 3.3 |
| U.S. History | A | 4.0 |
| Biology | B | 3.0 |
| Spanish III | B+ | 3.3 |
Sum of grade points: 3.7 + 3.3 + 4.0 + 3.0 + 3.3 = 17.3
Divided by 5 classes: 17.3 ÷ 5 = 3.46
Your semester GPA is 3.46.
Weighted GPA: accounting for course difficulty
Many high schools award bonus grade points for honors, AP (Advanced Placement), IB (International Baccalaureate), and dual-enrollment courses. The most common bonuses are:
- Honors courses: +0.5 grade points (so an A in Honors English = 4.5)
- AP or IB courses: +1.0 grade points (so an A in AP Chemistry = 5.0)
Weighted GPAs often top out at 5.0 rather than 4.0, although some schools use different caps. The bonus applies to every letter grade in that course — so a B in an AP class (3.0 + 1.0 = 4.0) outscores an A in a standard class (4.0) by exactly zero points, and a B+ in an AP class (3.3 + 1.0 = 4.3) edges ahead.
Using the same five classes from the example, with Algebra II upgraded to Honors and U.S. History to AP:
| Class | Grade | Level | Weighted grade points |
|---|---|---|---|
| English | A− | Standard | 3.7 |
| Honors Algebra II | B+ | Honors (+0.5) | 3.8 |
| AP U.S. History | A | AP (+1.0) | 5.0 |
| Biology | B | Standard | 3.0 |
| Spanish III | B+ | Standard | 3.3 |
Sum: 3.7 + 3.8 + 5.0 + 3.0 + 3.3 = 18.8
Divided by 5: 18.8 ÷ 5 = 3.76
The weighted semester GPA is 3.76, compared to the unweighted 3.46 — a 0.30-point bump from taking two advanced courses.
Credit-hour weighting (college GPA)
College GPA adds another layer: courses carry different numbers of credit hours (typically 1–4), and a 4-credit course should count more than a 1-credit elective. The formula becomes a weighted average:
College GPA = (sum of grade points × credit hours) ÷ (total credit hours)
Suppose a semester looks like this:
| Course | Credits | Grade | Grade points | Quality points (gp × cr) |
|---|---|---|---|---|
| Calculus I | 4 | B+ | 3.3 | 13.2 |
| Intro Chemistry | 3 | A− | 3.7 | 11.1 |
| English Comp | 3 | A | 4.0 | 12.0 |
| History seminar | 2 | B | 3.0 | 6.0 |
| PE elective | 1 | A | 4.0 | 4.0 |
Total quality points: 13.2 + 11.1 + 12.0 + 6.0 + 4.0 = 46.3
Total credit hours: 4 + 3 + 3 + 2 + 1 = 13
Semester GPA: 46.3 ÷ 13 = 3.56
Notice that a simple average of the five grade-point values
((3.3 + 3.7 + 4.0 + 3.0 + 4.0) ÷ 5 = 3.60) would give a different — and
incorrect — answer, because it ignores that Calculus carries four times the weight of PE.
Cumulative GPA across multiple semesters
Your cumulative GPA is not an average of your semester GPAs. It is a credit-weighted average of every course you have taken. The safest way to compute it is to keep a running total of total quality points and total credit hours across all semesters, then divide:
Cumulative GPA = total quality points (all semesters) ÷ total credit hours (all semesters)
For example, if Semester 1 produced 46.3 quality points over 13 credits (GPA 3.56), and Semester 2 produces 42.0 quality points over 12 credits (GPA 3.50), the cumulative GPA is:
(46.3 + 42.0) ÷ (13 + 12) = 88.3 ÷ 25 = 3.53
A simple average of the two semester GPAs ((3.56 + 3.50) ÷ 2 = 3.53) happens
to match here only because the credit loads were nearly equal. If one semester carried
significantly more credits, the averages would diverge.
Why one bad grade hurts less over time
As you accumulate more credit hours, the weight of any single course shrinks relative to the whole. An F in a 3-credit course during freshman year (adding 0 quality points while costing 3 credit hours) is a significant drag early on, but after 90 total credits that same F is diluted across a much larger denominator. This is the mathematical reason it becomes progressively harder — but not impossible — to rescue a cumulative GPA in later years.