How semester grades are calculated
In most U.S. high schools, the grade that lands on your transcript isn’t a quarter grade. It’s the semester grade, built from the grading periods inside that semester (usually two quarters, sometimes three six-week terms) plus a semester exam if the class has one. Each piece gets a weight, and the semester grade is the weighted average of the pieces.
Your handbook or course syllabus lists the weights. Look for a line like “Quarter 1: 40%, Quarter 2: 40%, Semester exam: 20%.” If you can’t find one, ask the teacher or the counseling office; guessing the split is the main way this number comes out wrong.
When the weights add up to 100, the bottom of the fraction is 100, and each piece simply contributes its share. Running it backward gives the exam score you need:
Common weightings
There’s no national rule. A 40/40/20 split is common; Carmi-White County High School in Illinois, for example, posted that exact formula (first quarter 40%, second quarter 40%, semester exam 20%) in a December 2020 notice to families. Other schools give the exam more or less weight, or have no exam at all. Here’s what the same grades (88 and 92 in the quarters, 78 on the exam) turn into under a few example splits. Every one of them is editable in the calculator.
| Example split (Q1 / Q2 / exam) | Semester grade | Letter |
|---|---|---|
| 40 / 40 / 20 | 87.6 | B+ |
| 45 / 45 / 10 | 88.8 | B+ |
| 37.5 / 37.5 / 25 | 87.0 | B+ |
| 50 / 50, no exam | 90.0 | A- |
Same student, same work, and a 3-point spread depending on the policy. That’s why the weights matter as much as the scores.
Two worked examples
Finding the semester grade. You finished Q1 with an 88 and Q2 with a 92, then scored 78 on the semester exam. The split is 40/40/20. Multiply: 0.40 × 88 = 35.2, 0.40 × 92 = 36.8, and 0.20 × 78 = 15.6. Add them and you get 87.6%, a B+. Your quarters averaged 90, so the exam cost you 2.4 points, enough to drop you from an A- to a B+.
Working backward from a goal. You have an 84 in Q1 and a 79 in Q2, and you want to hold on to a B- (80) for the semester. With 40/40/20, your quarters already lock in 33.6 + 31.6 = 65.2 points. You need 14.8 more from an exam worth 20, and 14.8 ÷ 0.20 = 74%. If the class had no exam and the quarters counted 50/50, you’d already be at 81.5.
How much the semester exam can move your grade
The heavier the exam, the more it can lift or sink you. Starting from quarters that average 85:
| Exam weight | Exam 100% | Exam 60% |
|---|---|---|
| 10% | 86.5 | 82.5 |
| 15% | 87.25 | 81.25 |
| 20% | 88.0 | 80.0 |
| 25% | 88.75 | 78.75 |
| 30% | 89.5 | 77.5 |
At 10%, a great exam and a rough one are only 4 points apart. At 30%, the gap is 12 points, more than a full letter. If you’re juggling several exams, the table is a decent guide to where your study hours buy the most.
Semester grade vs. final grade calculator
The final grade calculator assumes your class has one running grade and a final worth a set share of it. That fits a college course, or a high school class where the portal shows a single semester average. This page fits classes where each quarter closes with its own grade and the semester grade combines them later. If you’re not sure what a quarter grade is in the first place, work it out from your category weights with the grade calculator, then bring it here.
Where schools differ
- Letters instead of percentages. Some districts combine quarter letter marks using a lookup chart or grade points, not percentages. If your report card shows only letters, ask how they’re combined before trusting a percent.
- Rounding. A quarter might show as 89 on the report card but sit at 89.4 in the gradebook. Use the unrounded number if you can see it, and aim a little above any cutoff.
- Credit rules. Some schools add conditions beyond the average. The Carmi-White County notice above also requires passing two of the three pieces (both quarters and the exam) to earn credit.
- Exam exemptions. Some schools let students with high grades or good attendance skip the exam. Tick “No semester exam” and adjust the quarter weights to match.
- Letter cutoffs. The letter here uses the standard plus/minus scale (93 for an A, 90 for an A-), described on the methodology page. Your school may use a plain 90/80/70 scale.
Once each semester grade is final, the GPA calculator turns them into a term GPA.