How to Calculate GPA
Turn each letter grade into grade points, multiply by the course's credit hours, add the results, then divide by the credit hours. The GPA calculator does it for a whole transcript, and the arithmetic below is the same arithmetic by hand.
GPA formula
GPA is total quality points divided by total credit hours. Quality points are one course's grade points times its credit hours, so a 4-hour course moves the average 4 times as far as a 1-hour lab with the same letter on it.
The grade points come from the school's own table. This term is worked on the plus/minus 4.0 table, where an A- is 3.70 and a B+ is 3.30.
Worked example: one term of five courses
| Course | Letter | Credit hours | Grade points | Quality points |
|---|---|---|---|---|
| English Composition | B+ | 3 | 3.30 | 9.90 |
| Calculus I | A- | 4 | 3.70 | 14.80 |
| US History | B | 3 | 3.00 | 9.00 |
| Chemistry Lab | A | 1 | 4.00 | 4.00 |
| Spanish II | C+ | 3 | 2.30 | 6.90 |
| Total | 14 | 44.60 |
Source: Academic grading in the United States, read 2026-09-20.
44.60 quality points divided by 14 credit hours is a term GPA of 3.19. Nothing is rounded before that last step, because rounding each course first moves the answer.
Cumulative GPA across terms
A cumulative GPA runs the same division over every term at once: all the quality points over all the credit hours. Add a 4-hour summer term at 4.00 to that fall term of 14 hours at 3.19 and the cumulative GPA is 60.60 quality points over 18 hours, which is 3.37.
Averaging the two term GPAs would have given 3.59, because that treats a 4-hour term as the equal of a 14-hour one. The cumulative GPA calculator takes the terms and does the credit-hour division.
Weighted GPA for Honors and AP courses
A weighted GPA adds points for course difficulty before the division. On this district's table an Honors course adds 0.50 and an AP, IB or Dual Enrollment course adds 1.00, so an A in AP US History is worth 5.00 rather than 4.00. Beside a B in Algebra II, that is 4.00 weighted against 3.50 unweighted.
Source: St. Johns County School District: GPAs Explained, read 2026-09-20.
St Johns County publishes Standard 4/3/2/1/0, Honors 4.5/3.5/2.5/1.5/0 and AP, IB, Dual Enrollment or AICE 5/4/3/2/0 on whole letters, so a plus or minus counts as its whole letter here. The bonus amount is set district by district.
Every point table on this page, including the 4.33 scale some colleges report on, is set out on the GPA scale page, and the letter each percentage earns comes from the grading scale page. The weighted GPA calculator takes your district's bonus rather than this one.