Learn how to calculate test scores, convert raw scores to percentages, and understand score adjustments. Covers the grade percentage formula, curves, and standardized test scoring.
Whether you're a student checking your exam result or a teacher designing a grading rubric, calculating test scores follows straightforward formulas. Understanding how raw scores convert to percentages, how curves work, and how standardized tests scale their results makes you a more informed test-taker and a better evaluator of academic performance.
Percentage Score = (Points Earned ÷ Total Points Possible) × 100
Standard US grading scale (varies by institution):
| Percentage | Letter Grade | GPA Points |
|---|---|---|
| 93–100% | A | 4.0 |
| 90–92% | A− | 3.7 |
| 87–89% | B+ | 3.3 |
| 83–86% | B | 3.0 |
| 80–82% | B− | 2.7 |
| 77–79% | C+ | 2.3 |
| 73–76% | C | 2.0 |
| Below 60% | F | 0.0 |
Curving adjusts test scores when the test was more difficult than intended, or to normalize grade distribution. Two common methods:
Add a fixed number of points to every score:
If the highest score was 87% and the teacher curves so the highest becomes 100%: add 13 points to everyone's score.
Your raw 78% + 13 = 91% curved score
A common curve formula: Curved Score = √(Raw Score ÷ Total Points) × Total Points
Example: 64/100 raw → √(64/100) × 100 = √0.64 × 100 = 0.8 × 100 = 80 curved
This method brings low scores up significantly while barely affecting high scores.
Lower the cutoffs for each letter grade (e.g., B is now 75–82 instead of 83–86). This doesn't change raw scores but changes how they map to letter grades.
To find how many correct answers you need for a target score:
Questions Needed = Target% × Total Questions ÷ 100
Example: Need 80% on a 45-question test:
45 × 0.80 = 36 → need at least 36 correct answers
Some standardized tests (historically SAT, many competitive exams) deduct points for wrong answers to discourage guessing:
Score = Correct − (Wrong ÷ (n−1))
Where n = number of choices per question. For a 4-choice question: Score = Correct − (Wrong ÷ 3)
Strategic implication: If you can eliminate at least one answer choice, guessing is expected-value positive. If you can't eliminate any, expected value is zero (break-even).
These scaled scores are designed so a specific raw score always maps to the same percentile, adjusted for test difficulty across different test versions (equating).
Minimum points needed = (Pass percentage ÷ 100) × Total points
Example: 60% passing threshold on a 75-point exam: 0.60 × 75 = 45 points minimum
Use our free Test Score Calculator — results appear as you type. No sign-up needed!
🚀 Open Test Score Calculator Free