A+ Test Grade Calculator, Score and Letter Grade Instantly
By Shihab Mia ยท Updated 2026-07-06
Reference grading chart
Wrong to score, out of 25| Wrong | Correct | Score | Grade |
|---|
This test grade calculator turns the number of questions on a test and the number a student missed into a clean percentage score and a letter grade in one step. The math is simple and standard: correct equals total minus wrong, the score is correct divided by total times 100, and the letter grade follows the usual US scale of A for 90 and up, B for 80s, C for 70s, D for 60s, and F below 60. It works like a classic EZ grader, and it also builds a full grading chart so you can read off the score for every possible number wrong at a glance.
What is the Test Grade Calculator?
Grading a stack of papers by hand is slow and error prone, especially when every test has a different number of questions. The core idea behind an EZ grader is to remove the mental arithmetic: you tell it how many questions the test had and how many the student got wrong, and it hands back the percentage and letter grade. This tool does exactly that, and because it is a live calculator rather than a fixed paper wheel, it handles any number of questions, not just the common ones printed on a physical grader.
The calculation is deliberately transparent so you can trust it and reproduce it by hand. First it finds the number correct by subtracting wrong from total. Then it divides correct by total and multiplies by 100 to get a percentage, rounded to two decimal places so borderline scores are not hidden. Finally it maps that percentage onto the standard letter scale. Nothing is weighted or curved; this is the raw score most teachers start from before any extra credit or grading policy is applied.
A small but important detail is the toggle between counting wrong answers and counting correct answers. Some teachers mark the number missed at the top of a paper, while others tally the number right. Rather than force you to do the subtraction yourself, the calculator lets you switch modes, and it validates that the number you enter can never exceed the total number of questions. If you type a value that is impossible, such as 30 wrong on a 25 question test, it shows a friendly error instead of a nonsense score.
The reference grading chart underneath the result is what makes this a genuine replacement for a physical grader. It lists every number wrong from zero up to the total, alongside the matching number correct, the percentage, and the letter grade, and it highlights the row for the score you just entered. You can scan the whole test in one look, mark a class set quickly by reading straight off the chart, or print the page and keep it next to you while you grade. Everything runs in your browser, so no scores are uploaded and the tool works even offline once the page has loaded.
When to use it
- Grading a stack of quizzes or tests quickly by entering the number of questions once and reading the score for each paper off the chart.
- Turning a raw mark like 22 out of 25 into a percentage and letter grade without a calculator.
- Checking your own score after a practice test so you know where you stand on the letter scale.
- Building a quick reference sheet for a test with an unusual number of questions, such as 17 or 43.
- Helping a student understand how many more questions they needed right to move up a letter grade.
- Replacing a lost or borrowed physical EZ grader wheel with a printable chart on any device.
How to use the Test Grade Calculator
- Enter the total number of questions on the test in the first box.
- Choose whether you are entering the number wrong or the number correct using the Counting selector.
- Type that number in the second box; the score and letter grade update instantly.
- Read the percentage, the correct out of total, and the letter grade in the result panel.
- Scroll the grading chart to see every possible score, or click Copy result to grab the summary.
Formula & method
Worked examples
A 25 question test with 3 answers marked wrong.
- Total questions = 25, number wrong = 3.
- Correct = 25 - 3 = 22.
- Score = (22 / 25) x 100 = 88%.
- 88 falls in the 80 to 89.99 band, so the letter grade is B.
Result: 88%, 22 out of 25, grade B
A 40 question exam where the student got 34 correct.
- Switch the Counting selector to Number correct.
- Total questions = 40, number correct = 34, so wrong = 40 - 34 = 6.
- Score = (34 / 40) x 100 = 85%.
- 85 is in the 80s band, so the letter grade is B.
Result: 85%, 34 out of 40, grade B
Standard US letter grade scale used by this calculator
| Letter grade | Percentage range | Meaning |
|---|---|---|
| A | 90 to 100 | Excellent |
| B | 80 to 89.99 | Good |
| C | 70 to 79.99 | Satisfactory |
| D | 60 to 69.99 | Passing but weak |
| F | Below 60 | Failing |
Sample grading chart for a 20 question test
| Number wrong | Number correct | Score | Grade |
|---|---|---|---|
| 0 | 20 | 100% | A |
| 1 | 19 | 95% | A |
| 2 | 18 | 90% | A |
| 3 | 17 | 85% | B |
| 4 | 16 | 80% | B |
| 5 | 15 | 75% | C |
| 6 | 14 | 70% | C |
| 7 | 13 | 65% | D |
| 8 | 12 | 60% | D |
| 9 | 11 | 55% | F |
Common mistakes to avoid
- Mixing up number wrong and number correct. Entering the number correct while the tool is set to count wrong answers flips the score completely. Check the Counting selector matches what you are typing. On a 25 question test, 3 wrong is 88% but 3 correct is only 12%.
- Entering more wrong than there are questions. The number wrong can never be larger than the total. If you type 30 wrong on a 25 question test the calculator shows an error rather than a negative or fake score. Double check the total first.
- Assuming the letter scale is universal. This tool uses the common A to F scale with 90, 80, 70, 60 cutoffs. Some schools use different thresholds, plus and minus bands, or a curve. Read the percentage and apply your own grading policy if it differs.
- Forgetting that unequal question weights change the math. This calculator assumes every question is worth the same. If some questions carry more points, use a points based grade calculator instead, because a simple count of wrong answers will not reflect the true score.
Glossary
- EZ grader
- A tool, originally a physical sliding chart, that converts the number of questions and the number missed into a percentage score.
- Percentage score
- The share of questions answered correctly, written out of 100, calculated as correct divided by total times 100.
- Letter grade
- A letter such as A, B, C, D, or F assigned to a percentage range to summarise performance.
- Total questions
- The number of items on the test that count toward the score, used as the denominator.
- Number wrong
- The count of questions answered incorrectly or left blank, subtracted from the total to find the number correct.
- Grading scale
- The set of percentage cutoffs that decide which letter grade a score earns, such as 90 for an A.
Frequently asked questions
How do you calculate a test grade?
Divide the number of questions answered correctly by the total number of questions, then multiply by 100 to get a percentage. For example, 22 correct out of 25 is 22 divided by 25 times 100, which equals 88%. Then match that percentage to a letter grade, so 88% is a B on the standard scale.
What grade is 22 out of 25?
22 out of 25 is 88%, which is a B on the standard US letter scale where B covers 80 to 89.99.
What letter grade is 88 percent?
88 percent is a B. On the standard scale an A is 90 and above, a B is 80 to 89.99, a C is 70 to 79.99, a D is 60 to 69.99, and anything below 60 is an F.
Can I enter the number correct instead of the number wrong?
Yes. Switch the Counting selector to Number correct and enter how many the student got right. The calculator works out the number wrong for you and gives the same score and grade.
Does this work like an EZ grader wheel?
Yes. It does the same job as a physical EZ grader but for any number of questions, and it prints a full chart showing the score for every possible number wrong so you can grade a whole class from one look.
How is the percentage rounded?
The percentage is rounded to two decimal places, so a score like 66.6666 shows as 66.67%. The letter grade is then based on that rounded percentage.
What if my school uses a different grading scale?
This tool uses the common 90, 80, 70, 60 cutoffs without plus or minus. If your school uses different thresholds or a curve, use the percentage the tool gives and apply your own scale to it.
Is my grading data private?
Yes. Everything is calculated locally in your browser using JavaScript. No scores, question counts, or results are uploaded to any server.