To average grades, you add up all your scores and divide by the number of scores. If you earned 88, 92, 76, and 84 on four tests, your average is (88 + 92 + 76 + 84) ÷ 4 = 85. That’s the basic method, but many courses use weighted categories, credit hours, or other adjustments that change the math. Here’s how each approach works.
The Simple Average
A simple average (also called an arithmetic mean) treats every grade equally. You add all the grades together, then divide by how many there are. If you got a 90 on one quiz and a 70 on another, your average is (90 + 70) ÷ 2 = 80.
This works well when every assignment counts the same. But most courses don’t work that way. A final exam usually matters more than a single homework assignment, which is where weighted averages come in.
Weighted Averages by Category
Most college and many high school courses split your grade into categories, each worth a set percentage of your final grade. A typical breakdown might look like this:
- Homework: 15%
- Discussions or participation: 20%
- Quizzes: 25%
- Exams: 40%
All the categories should add up to 100%. To calculate your weighted grade, first find your average within each category. Then multiply each category average by its weight (expressed as a decimal), and add those results together.
Say your homework average is 95, your discussion average is 88, your quiz average is 82, and your exam average is 74. Your final grade would be: (95 × 0.15) + (88 × 0.20) + (82 × 0.25) + (74 × 0.40) = 14.25 + 17.60 + 20.50 + 29.60 = 81.95. Even though a simple average of those four numbers is 84.75, the weighted result is lower because exams carry the most weight and that’s where you scored lowest.
This is why it pays to know the weight of each category early in the semester. Scoring a 95 on homework that counts for only 15% of your grade won’t rescue a 74 exam average that counts for 40%.
Averaging Letter Grades With Credit Hours
When you’re calculating your GPA across multiple courses, you can’t just average the letter grades directly because courses carry different numbers of credit hours. A 4-credit class should influence your GPA twice as much as a 2-credit class.
Here’s the process. First, convert each letter grade to its point value on the standard 4.0 scale:
- 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
Next, multiply each grade’s point value by the number of credit hours for that course. These are called quality points (or grade points). Then add up all the quality points and divide by the total number of credit hours.
For example, imagine you took three courses this semester: a 4-credit biology class (B+), a 3-credit English class (A), and a 3-credit history class (B-). Your quality points are (3.3 × 4) + (4.0 × 3) + (2.7 × 3) = 13.2 + 12.0 + 8.1 = 33.3. Divide that by your 10 total credit hours: 33.3 ÷ 10 = 3.33 GPA.
To find your cumulative GPA across multiple semesters, total up the quality points and credit hours from every term, then divide. You don’t average your semester GPAs together, because that would treat a 12-credit semester the same as a 16-credit semester.
Weighted vs. Unweighted GPA
An unweighted GPA uses the standard 4.0 scale, where an A is worth 4.0 no matter what class you took. A weighted GPA extends the scale beyond 4.0 to reward students who take harder courses. In a weighted system, an A in an AP, IB, or honors class might be worth 4.5 or 5.0 points instead of the usual 4.0.
The exact bump depends on your school’s policy. Some schools add 0.5 points for honors courses and 1.0 for AP or IB. Others use different scales. This means a student taking mostly AP classes could end up with a weighted GPA above 4.0, which isn’t possible on an unweighted scale. If you’re calculating your own GPA to compare it with college admission averages, check whether the school reports weighted or unweighted figures so you’re comparing the same thing.
Dropped Scores and Replacement Exams
Many instructors let you drop your lowest score on quizzes or exams. If your professor gives three exams each worth 20% of your grade and drops the lowest, your two remaining exams each count for 30% instead. This means fewer makeup exams and a cushion if you bomb one test.
Some courses offer a replacement exam instead of a straight drop. You take an additional test at the end of the semester, and if that score is higher than your worst earlier exam, it replaces it. The advantage is that you’re still responsible for all the material, which can double as final exam prep.
Another approach is progressive weighting, where later exams count more than earlier ones. Your first test might be worth 15%, the second 20%, and the third 25%. This rewards improvement over the semester and gives you time to adjust to a professor’s testing style.
When dropped scores or replacements are in play, recalculate your average after the adjustment. Remove the dropped grade from your list (or swap in the replacement), then average the remaining scores using whatever weights apply.
A Quick Way to Check Your Standing
If you want to figure out what grade you need on a final exam to hit a target, work the weighted average formula backward. Multiply each category average you already know by its weight, add them up, then figure out what score in the remaining category gets you to your goal.
Say exams are worth 40% of your grade, and your other categories combine to give you 52 points out of 60 possible (the other 60% of your grade). You need an 80 overall. That means you need 80 – 52 = 28 points from exams, and 28 ÷ 0.40 = 70. You’d need a 70 average on your exams to finish the course with an 80.
Running this calculation a few weeks before finals can help you prioritize your study time across courses, focusing energy where it will move your grade the most.