To calculate your GPA on the 4.0 scale, multiply each course grade by its credit hours, add those products together, and divide by the total credits. As a formula:
GPA = sum of (credits × grade points) ÷ total credits
The product of credits and grade points for one course is called its quality points. So GPA is just your total quality points divided by your total credits. The GPA calculator runs this for every course at once, but the method is easy to do by hand once you have the grade point table.
The letter-to-grade-point table
First convert each letter grade to its grade point value. A standard 4.0 scale looks like this:
| Letter | Grade points |
|---|---|
| A / 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 |
Plus and minus scales vary by school. Many cap A+ at 4.0, but some award 4.3. A handful of schools drop plus and minus entirely, so every B is 3.0. Use the scale your registrar publishes, not a generic one.
A worked example
Say you took three courses in one term:
- A 4-credit course with an A (4.0 grade points)
- A 3-credit course with a B+ (3.3 grade points)
- A 3-credit course with a C (2.0 grade points)
Work out the quality points for each course by multiplying credits by grade points:
- 4 × 4.0 = 16.0
- 3 × 3.3 = 9.9
- 3 × 2.0 = 6.0
Add the quality points: 16.0 + 9.9 + 6.0 = 31.9.
Add the credits: 4 + 3 + 3 = 10.
Divide: 31.9 ÷ 10 = 3.19.
So the term GPA is 3.19. The GPA calculator shows this breakdown row by row, which makes it easy to check before you trust a number.
Why credit weighting matters
Credits are why a GPA is not just the average of your letter grades. A course worth more credits carries more weight, so it pulls the GPA further.
In the example above, the 4-credit A counts more than either 3-credit course. If you swapped that A for an A in the 3-credit C slot instead, the same set of letters would give a different GPA, because the heavy course changed grade. This is also why one bad grade in a high-credit course hurts more than the same grade in a 1-credit elective, and why retaking a heavy course can move your average more than retaking a light one.
Calculating a cumulative GPA
A cumulative GPA spans every term, not just one. The method is the same, you just include all the courses.
Add the quality points from every course across all terms, then divide by the total credits across all terms. For example, if your first term gave 31.9 quality points over 10 credits and your second term gave 42.0 quality points over 12 credits:
- Total quality points: 31.9 + 42.0 = 73.9
- Total credits: 10 + 12 = 22
- Cumulative GPA: 73.9 ÷ 22 = 3.36
Do not average the two term GPAs (3.19 and 3.50) directly. That would give 3.345, which is wrong here because the terms carried different credit loads. Averaging term GPAs only works when every term has the same number of credits. Adding quality points and dividing by total credits always works.
Check your scale, then check the math
The two things that throw GPA calculations off are using the wrong grade point values and forgetting to weight by credits. Confirm your school’s plus and minus scale, convert each letter carefully, and divide quality points by credits rather than averaging grades.
To see how honors and AP courses change the picture, read weighted versus unweighted GPA. To work backward from a target grade in one course, see what grade do I need on the final, or open the GPA calculator now.