How to Grade a Test: Percentage & Letter Grades
Grading a stack of tests doesn't need a spreadsheet. Learn the one formula, the letter-grade scale, and the shortcuts teachers use — then let the calculator do the arithmetic.
The formula
Every test grade is the same calculation:
| Formula | Example |
|---|---|
score % = (correct ÷ total) × 100 | 43 correct ÷ 50 questions × 100 = 86% |
score % = ((total − wrong) ÷ total) × 100 | (50 − 7) ÷ 50 × 100 = 86% |
If you grade by points rather than questions, swap in points: earned points ÷ total points × 100.
The letter grade scale
| Score | Letter grade | 50-question test | 20-question test |
|---|---|---|---|
| 90–100% | A | 45–50 correct | 18–20 correct |
| 80–89% | B | 40–44 correct | 16–17 correct |
| 70–79% | C | 35–39 correct | 14–15 correct |
| 60–69% | D | 30–34 correct | 12–13 correct |
| Below 60% | F | Fewer than 30 correct | Fewer than 12 correct |
Worked examples
- 50 questions, 7 wrong: 43 right → (43 ÷ 50) × 100 = 86% (B)
- 25 questions, 3 wrong: 22 right → (22 ÷ 25) × 100 = 88% (B)
- 100-question test: each question is worth 1% — 85 right = 85% (B)
- Partial credit: 41.5 of 50 points → (41.5 ÷ 50) × 100 = 83% (B)
Teacher shortcuts
- 100-question tests: the percentage equals the number correct — no math needed.
- Round consistently: decide once whether 86.4% rounds to 86 or 87 and apply it to every test.
- Set pass at the question level: for a 60% pass on a 50-question test, the cutoff is exactly 30 correct — mark those first, then grade the rest.
Use the easy grader
Enter the total questions and the number wrong — theEasy Grader returns the percentage and letter grade instantly, with a wrong-answers / correct-answers toggle.
Frequently asked questions
How do I calculate a test grade?+
Divide the number of correct answers by the total number of questions and multiply by 100. Example: 43 correct out of 50 → (43 ÷ 50) × 100 = 86%. If you know the number wrong, subtract it from the total first.
How many questions can I miss to get an A?+
An A is typically 90% or higher. On a 50-question test that means no more than 5 wrong (45 correct); on a 100-question test, no more than 10 wrong. If your school's A boundary is 93%, adjust accordingly.
What percentage is a passing grade?+
Most US schools treat 60% (D) as the minimum passing score, though some require 70% (C) or set their own policy. For GCSE-equivalent grading, the standard pass is around 35–44% of marks depending on the subject's boundaries.
How do I grade a 100-question test?+
Each question is worth exactly 1%: 100 correct = 100%, 85 correct = 85%, and so on. The number wrong is simply 100 minus the number right — the percentage and the count are the same number.
How do I grade a test with partial credit?+
Add up the points earned (including partial credit) and divide by the total points available, then multiply by 100. For example, 41.5 points out of 50 → (41.5 ÷ 50) × 100 = 83%.
What letter grade is 75%?+
75% is a C on the standard scale (70–79%). On a 20-question test that's 15 correct; on a 50-question test it's 37.5 correct, so 38 of 50.
How do I convert a test score to a letter grade?+
Use the standard scale: 90%+ = A, 80–89% = B, 70–79% = C, 60–69% = D, below 60% = F. If your school uses plus/minus or different cutoffs, apply those boundaries instead.
How many questions do I need right to pass a 50-question test?+
At a 60% pass mark you need 30 of 50 correct (20 wrong allowed). At a 70% pass mark you need 35 of 50 correct (15 wrong allowed). Use the easy grader to try any total.