To calculate your GPA, convert each letter grade to grade points (A = 4.0, B = 3.0, C = 2.0, D = 1.0, F = 0), multiply each by the class’s credits, add those products, and divide by your total credits. If every class has the same credits, you can simply average the grade points.
That’s the whole method. The rest of this guide is about the parts that trip people up: plus and minus grades, classes with different credits, weighted classes, and combining a new semester with the GPA you already have.
Step 1: Turn each letter grade into grade points
Most U.S. schools use a 4.0 scale with plus and minus grades. This is the most common version, and it’s the one GradeDuck’s calculators use (the College Board’s BigFuture chart is a simpler whole-letter version: A 90–100, B 80–89, C 70–79):
| Letter | Grade points | Typical percent |
|---|---|---|
| A+ / A | 4.0 | 93–100 |
| A- | 3.7 | 90–92 |
| B+ | 3.3 | 87–89 |
| B | 3.0 | 83–86 |
| B- | 2.7 | 80–82 |
| C+ | 2.3 | 77–79 |
| C | 2.0 | 73–76 |
| C- | 1.7 | 70–72 |
| D+ | 1.3 | 67–69 |
| D | 1.0 | 65–66 |
| F | 0.0 | below 65 |
Two things to check against your own school. First, some schools give an A+ a 4.3 instead of 4.0. Second, the percentage cutoffs vary a lot: plenty of schools call a 90 an A, not an A-. The grade points matter for the GPA, so if your report card shows letters, use the letters and ignore the percentages.
What goes wrong: converting a percentage straight to a GPA by dividing by 25 (so 88% becomes 3.52). It looks reasonable and it’s wrong. GPA is built from letter grades, so an 88 is a B+, which is 3.3.
Step 2: Find the credits for each class
Credits (sometimes called units or credit hours) tell you how much each class counts. In college, a lecture might be 3 credits and a lab 1 credit. In high school, a full-year class is often 1 credit and a semester class 0.5.
If your school gives every class the same weight, you can skip this step and treat each class as 1 credit. The math still works.
What goes wrong: forgetting that a 4-credit class counts four times as much as a 1-credit class. That’s the most common reason a hand-calculated GPA doesn’t match the one on a transcript.
Step 3: Multiply grade points by credits
The result for each class is called quality points, the term James Madison University’s registrar uses too. Here’s a real-looking college semester:
| Class | Grade | Points | Credits | Quality points |
|---|---|---|---|---|
| Calculus I | A | 4.0 | 4 | 16.0 |
| Intro to Psychology | B+ | 3.3 | 3 | 9.9 |
| Chemistry | C | 2.0 | 3 | 6.0 |
| Total | 10 | 31.9 |
Step 4: Divide total quality points by total credits
31.9 ÷ 10 = 3.19. That’s the semester GPA.
Notice what happens if you skip the credits and just average the three grade points: (4.0 + 3.3 + 2.0) ÷ 3 = 3.10. The A in the heaviest class pulls the real number up by almost a tenth of a point. It works the other way too, and that’s the uncomfortable part: a bad grade in a 4-credit class hurts more than the same grade in an elective.
If you’d rather not do this by hand, the GPA calculator does exactly these four steps and shows the quality points as it goes.
A high school example with the same credits
High school is often simpler because classes tend to carry the same credit. Take a junior with six classes:
- English: A-
- Algebra II: B+
- Biology: B
- U.S. History: A
- Spanish II: A-
- Art: A
Grade points: 3.7 + 3.3 + 3.0 + 4.0 + 3.7 + 4.0 = 21.7. Divide by 6 classes and the GPA is 3.62. The high school GPA calculator does this for all four years at once.
If some of these were Honors or AP classes, the school might also report a weighted GPA, where those classes earn extra points. That’s a separate calculation, and it’s covered in weighted vs. unweighted GPA.
Adding a new semester to your GPA
Your cumulative GPA covers every term so far. Don’t average your semester GPAs: go back to quality points instead. A 3.2 after 60 credits is 192 points; a new 15-credit term at 3.8 adds 57; so the new cumulative GPA is (192 + 57) ÷ 75 = 3.32, not the 3.50 a plain average suggests.
That’s the short version. What is cumulative GPA? covers it properly, including term vs. major GPA and retakes, and the cumulative GPA calculator does it for every semester at once.
What usually doesn’t count toward GPA
Schools differ, but these are the common rules:
- Pass/fail (P/NP) classes count toward your credits for graduation but not toward your GPA. Leave them out.
- Withdrawals (W) don’t count (does a W affect your GPA? covers the exceptions). A “WF” (withdrew failing) sometimes counts as an F, so check.
- Incompletes (I) usually don’t count until a grade replaces them.
- Transfer credits often count toward your degree but not your GPA at the new school.
- Retaken classes depend on the school. Many colleges replace the old grade with the new one; others count both attempts. This changes the math a lot, so look it up in your school’s catalog before you plan around a retake.
Why your number might not match the transcript
If you did everything above and your result is still a few hundredths off, it’s usually one of these:
- Your school’s scale is different. An A+ worth 4.3, or no minus grades at all, will shift the result.
- Rounding. Some schools truncate (3.596 becomes 3.59), as Georgia Tech does, and others round (3.60).
- A class you missed or a credit value you guessed. Check the credits on the transcript itself.
- Weighting. Your portal may show the weighted GPA by default.
The official GPA is always the one your registrar calculates. A calculator, including ours, is for checking that number and planning ahead. Every rule our tools use is listed on how we calculate.
What if your school doesn’t use letter grades?
Some report cards only show a 100-point average per class. To get a GPA from those, convert each class average to a letter first, then follow the steps above. With the plus/minus scale in the table, an 88 becomes a B+ (3.3) and a 94 an A (4.0). If your school uses a plain ten-point scale instead, the same 88 is just a B (3.0), which is why it’s worth finding your school’s own cutoffs before you trust the result. The GPA to percentage converter does the conversion in both directions, and the GPA scale guide compares the common scales side by side.
Planning ahead
Once you know how GPA is built, two questions usually follow. What do I need this term to reach a goal? And what do I need on the final to keep this grade? The raise GPA calculator answers the first. The final grade calculator answers the second. Both use the same arithmetic you just did by hand. To keep the same formula in a spreadsheet, here’s how to set it up in Excel or Google Sheets.