How to Calculate Your Test Grade
Whole questions vs partial credit
When every question is simply right or wrong, count and divide: 42 right out of 50 is 84%. The moment partial credit exists — a 6-point proof where you earned 4.5 — switch from counting questions to counting points. The formula is the same shape: points earned ÷ points possible × 100. Earn 78.5 points on a 92-point exam and your grade is 78.5 ÷ 92 × 100 = 85.3%.
One habit that prevents most errors: always divide by points possible, not the number of questions. A 20-question test where question 20 is worth 10 points isn't a 20-point test.
Quick conversions for common scores
| Score | Percentage | Typical letter |
|---|---|---|
| 18/20 | 90% | A− |
| 22/25 | 88% | B+ |
| 17/20 | 85% | B |
| 33/40 | 82.5% | B− |
| 23/30 | 76.7% | C |
| 45/60 | 75% | C |
| 21/25 | 84% | B |
| 27/30 | 90% | A− |
| 51/60 | 85% | B |
Letters use the common U.S. plus/minus scale (A− = 90–92, B+ = 87–89, B = 83–86, B− = 80–82, and so on). Your school's cutoffs may differ by a point or two — the percentage is the fact; the letter is the local translation.
How curves change your score
Two curve styles cover most classrooms. A flat add gives everyone the same bonus: the instructor adds 5 points, so your 84% becomes 89%. A highest-score-as-100 curve rescales to the top performer: if the best score was 92%, one common version adds the 8-point gap to everyone (84% → 92%), while a stricter version multiplies by 100/92 (84% → 91.3%). The two versions differ more as your score drops, so if the curve decides your letter grade, ask which one your instructor uses. Never assume a curve exists — calculate your raw grade first and treat any curve as a bonus.
Try it yourself: Test Grade Calculator (EZ Grader)
Enter questions right and questions total — percentage and letter grade appear instantly, partial credit included.
Frequently asked questions
How do I handle extra credit questions?
Add extra-credit points to your earned points but not to points possible. Earning 46 on a 50-point test that had 2 bonus points available is 46 ÷ 50 = 92% — which is why extra credit can push a score above 100%.
What percentage do I need to pass a test?
There's usually no per-test pass line — tests feed into a course average, and the course has the pass line (typically 60–70%). Exceptions exist (certification exams, some nursing programs), so check the syllabus for the phrase "minimum score."
Do wrong answers ever subtract points?
On most classroom tests, no — blank and wrong both score zero. Some standardized tests historically penalized guessing, but the major U.S. college-admissions tests no longer do. Unless the instructions say otherwise, answer everything.