After a test, teachers hand back a paper with "18/22" or "85" and move on. If you're managing your own GPA, tracking study effectiveness, or grading homework as a tutor, you need to calculate test score percentage fast and correctly — including partial credit and weighted questions.
The basic formula
Percentage = (Points earned ÷ Total points possible) × 100
That's the whole formula. What makes it tricky is figuring out "points earned" when questions have partial credit, weighted sections, or extra credit.
Simple example
Test with 25 questions, 4 points each (100 total). You got 21 correct.
- Points earned: 21 × 4 = 84
- Percentage: 84 ÷ 100 × 100 = 84%
With partial credit
Essay and problem-solving sections rarely award 100% or 0% — partial credit is the norm.
Test breakdown: 10 multiple choice (2 pts each) + 4 short answer (5 pts each) + 2 essays (30 pts each).
Your scores: 9/10 MC, 17/20 SA, 52/60 essays.
- MC: 18 earned / 20 possible
- SA: 17 earned / 20 possible
- Essay: 52 earned / 60 possible
- Total: 87 earned / 100 possible = 87%
Letter grade conversion
Most US schools use the 10-point scale:
| Percentage | Letter |
|---|---|
| 90–100 | A |
| 80–89 | B |
| 70–79 | C |
| 60–69 | D |
| Below 60 | F |
With +/-:
- A+: 97-100 | A: 93-96 | A-: 90-92
- B+: 87-89 | B: 83-86 | B-: 80-82
- C+: 77-79 | C: 73-76 | C-: 70-72
- Same pattern down through D-
Different scales
Some teachers use stricter or easier scales:
- 7-point scale: A = 93-100, B = 85-92, C = 77-84, D = 70-76 (harder)
- Rounded/generous: A = 89.5+, B = 79.5+ (1 point favored the student)
- Standards-based: 4 = mastery, 3 = proficient, 2 = developing, 1 = below (no percentage at all)
Check the syllabus — a 92 is an A- on a 10-point scale and a B on a 7-point scale.
Curved scores
A "curve" adjusts raw scores upward based on class performance:
- Fixed curve: "5 points added to every score"
- Scaled curve: "Top score = 100%, all others scaled proportionally"
- Bell curve: grades distributed to match a predetermined curve — top 10% A, next 20% B, etc.
- Square root curve: Adjusted score = √raw × 10 (raises lows more than highs)
Ask your teacher which method before calculating. A raw 82 could be anywhere from a 79 (no curve) to a 91 (top-score scale).
Weighted sections
Some tests weight sections differently. Example:
- Grammar section: 30% of test
- Reading section: 30%
- Writing: 40%
Your scores: 85 grammar, 90 reading, 78 writing.
Test percentage = (0.30 × 85) + (0.30 × 90) + (0.40 × 78) = 25.5 + 27 + 31.2 = 83.7%
Extra credit
Extra credit usually comes in two flavors:
- Bonus points: Score becomes (earned + bonus) ÷ base possible × 100. A 92 becomes 95 with 3 bonus points on a 100-point test.
- Extended total: Score becomes (earned) ÷ (base + bonus) × 100. Rarer; teachers should announce this explicitly.
Back-calculating from a percentage
If a teacher tells you "you got an 88%," how many points did you earn? On a 120-point test:
- Points earned = 0.88 × 120 = 105.6 points
Useful when teachers only report the percentage and you want to track raw points throughout the course.
Quick calculation for common totals
- Out of 20: Multiply by 5 (16 = 80%, 18 = 90%)
- Out of 25: Multiply by 4 (22 = 88%, 23 = 92%)
- Out of 40: Multiply by 2.5
- Out of 50: Multiply by 2
- Out of 75: Divide by 75, then × 100 (no shortcut)
Percentage vs percentile
Don't confuse these:
- Percentage: Your score relative to maximum possible (75% = 75 of 100 points)
- Percentile: Your rank relative to other students (75th percentile = scored higher than 75% of the class)
An 85% might be 70th percentile (easy test) or 95th percentile (hard test).
Dropped scores and replacement
Many teachers let students drop their lowest test score or replace it with the final exam score. This changes how to compute your current percentage:
- Drop-the-lowest: calculate the weighted average using only the remaining tests — don't forget to remove both the score AND its weight from the denominator
- Replace-with-final: substitute the final exam score in place of the lowest, but keep total count the same
- Ask first: "drop one" policies sometimes apply only if you took all other tests — missing a test and then dropping a low one is usually not allowed
If you're near a letter-grade boundary, ask the teacher which scores will be dropped before computing — one percentage point can mean a full letter grade.
Self-grading for practice
For practice tests, online quiz tools, or tutoring:
- Score every question — never skip "I got this one right, I'm sure" without checking — check every answer
- Track by category — note which question types you miss (algebra vs geometry; vocabulary vs comprehension)
- Record percentage + date — plotting practice scores over time reveals whether you're actually improving
- Set target scores — decide what percentage you'd consider "ready" before taking the real test
Categorical tracking often reveals patterns like "I score 95% on algebra and 62% on geometry" — pointing you directly at where to study.
Common calculation mistakes
- Forgetting to include skipped questions in the denominator — a blank question is wrong, not removed
- Counting extra credit incorrectly — 102/100 with 2 bonus points = 102%, not "A+ no matter what"
- Rounding too early — always calculate to two decimals before rounding at the end
- Mixing up "points missed" vs "points earned" — if 5 points deducted, you earned total minus 5, not just 5
Calculate your scores fast
Our test score calculator converts raw scores to percentages and letter grades instantly — and handles weighted sections, partial credit, and custom grading scales.