Work out a test score as a percentage and a letter grade. Enter the number of questions (or total points) and how many were wrong, and the calculator shows the score, the working and a full grading chart for every possible number wrong. Teachers use the chart to mark a whole stack of papers; students use it to check a result.
How to use the test score calculator
- Enter the total: the number of questions, or the total points if questions carry different marks.
- Choose whether you know the number wrong or the number correct, and enter it. Half marks such as 2.5 are fine.
- Read the percentage and letter grade. Your row is highlighted in the chart below it.
How to calculate a test score
Divide the points you got by the points available and multiply by 100.
Score (%) = correct ÷ total × 100
For example, 17 correct out of 20 is 17 ÷ 20 × 100 = 85%. If you know the number wrong, subtract it from the total first: 20 − 3 = 17 correct.
Letter grade scale
The letter grade uses the common US scale below. Many schools use it, but some set their own cut-offs, so check your syllabus if a grade is close to a boundary.
| Letter | Percentage |
|---|---|
| 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 |
| D+ | 67–69 |
| D | 63–66 |
| D− | 60–62 |
| F | Below 60 |
Quick reference: common test lengths
| Test length | 1 wrong | 2 wrong | 3 wrong | 5 wrong |
|---|---|---|---|---|
| 10 questions | 90% | 80% | 70% | 50% |
| 20 questions | 95% | 90% | 85% | 75% |
| 25 questions | 96% | 92% | 88% | 80% |
| 40 questions | 97.5% | 95% | 92.5% | 87.5% |
| 50 questions | 98% | 96% | 94% | 90% |
Each question on a 20-question test is worth 5%, on a 25-question test 4%, and on a 50-question test 2%. That is why one mistake costs far more on a short quiz than on a long exam.
Frequently asked questions
How many can I get wrong and still pass?
With a 60% pass mark you can miss 40% of the questions: 8 out of 20, 10 out of 25 or 20 out of 50. Find the last row in the chart with a D− or better.
What if questions are worth different marks?
Enter total points instead of questions. A test with 10 questions worth 2 marks and 5 worth 4 marks has 40 points; if you lost 6 marks, enter 40 and 6.
Is this the same as an EZ grader?
Yes. An EZ grader is a printed chart that lists the score for each number wrong, which is what the table under the calculator does for any test length up to 200.
How do I turn test scores into a class grade?
Tests are usually one weighted part of the final grade. Use the grade calculator to combine tests, homework and quizzes by their weights, or the final grade calculator to see what you need on the final exam.
How to cite this tool
Using this tool for coursework, a report or research? You can cite it like this (APA 7th edition):
Kumar, M. (2026). Test Score Calculator [Online tool]. FreeToolsLand. https://freetoolsland.com/test-score-calculator/
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