Two students both got three A's and a C. One has a 3.5 GPA, the other a 3.2. Same grades, different number — because GPA isn't an average of your letters, it's a weighted average where harder, higher-credit courses count for more. Once you see how the weighting works, calculating your own GPA takes about two minutes and you can predict exactly what next semester needs to be.
What GPA actually measures
GPA (Grade Point Average) converts your letter grades into a single number on a scale, almost always 4.0 in the US. Each letter becomes a point value:
Letter | Grade points |
A | 4.0 |
A− | 3.7 |
B+ | 3.3 |
B | 3.0 |
B− | 2.7 |
C+ | 2.3 |
C | 2.0 |
D | 1.0 |
F | 0.0 |
The key insight most people miss: GPA is weighted by credit hours. A 4-credit course affects your GPA nearly twice as much as a 2-credit one. That's why the same letters can produce different GPAs.
The formula
GPA = Total quality points ÷ Total credit hours
Where quality points for each course = grade points × credit hours.
Three steps:
Multiply each course's grade points by its credit hours.
Add up all those quality points.
Divide by the total number of credit hours.
A worked example
Say you took four courses this semester:
Course | Grade | Points | Credits | Quality points |
Biology | A | 4.0 | 4 | 16.0 |
Calculus | B | 3.0 | 3 | 9.0 |
History | A− | 3.7 | 3 | 11.1 |
Elective | C | 2.0 | 2 | 4.0 |
Total quality points = 16.0 + 9.0 + 11.1 + 4.0 = 40.1. Total credits = 4 + 3 + 3 + 2 = 12.
GPA = 40.1 ÷ 12 = 3.34.
Notice the C in the 2-credit elective barely dented your GPA, while the A in 4-credit Biology carried enormous weight. The GPA calculator does this whole table for you — just enter grades and credits.
Weighted vs unweighted GPA
Unweighted GPA caps every course at 4.0, regardless of difficulty. An A in gym equals an A in AP Physics.
Weighted GPA gives harder classes a bonus — honors and AP courses often use a 5.0 scale, so an A in AP Physics is worth 5.0. This is why some high school students report GPAs above 4.0.
When a college asks for your GPA, check which one they want — mixing the two up is the most common GPA mistake there is.
Cumulative GPA vs semester GPA
Your semester GPA covers one term. Your cumulative GPA covers everything you've taken. To find cumulative GPA, use the same formula across all courses ever — total quality points across every semester divided by total credits across every semester.
A practical consequence: the more credits you've already banked, the harder it is to move your cumulative GPA. A single great semester barely nudges a number built on 90 prior credits. Early grades set the foundation.
Predicting what you need
Because GPA is just a weighted average, you can work backwards. Want to reach a 3.5 cumulative? Multiply 3.5 by your projected total credits to get the quality points you'd need, subtract what you already have, and you know exactly what this semester must deliver. If you're averaging non-credit-weighted scores (like a set of test grades), the average calculator handles the simpler mean, and the percentage calculator converts raw scores to percentages first.
The bottom line
GPA isn't the average of your letter grades — it's your grade points weighted by credit hours, totaled and divided. Know whether a school wants weighted or unweighted, remember that high-credit courses move the needle most, and run the numbers with the GPA calculator whenever you want to check where you stand or plan the semester ahead.