Test Grade Calculator
Miss 3 questions out of 20 and you score 85%, a B. This test grade calculator shows your percentage score and letter grade from two simple inputs: total questions and questions missed. It works well for quizzes, classroom tests, practice exams, and answer keys where every question counts the same. Enter the full question count, enter how many you got wrong, and the tool returns the exact percent, the number correct, and the standard letter grade. That makes it useful when a teacher needs a fast grading check, when a student wants to see how much one mistake changes the result, or when a parent is double-checking a graded paper at home.
Quick answer
The calculator first subtracts wrong answers from total questions to find how many answers were correct.
Score
85%
Letter grade
B
Correct answers
17 of 20
What this tells you
- •The calculator first subtracts wrong answers from total questions to find how many answers were correct.
- •It then divides correct answers by total questions and multiplies by 100 to get the test percentage.
- •Letter grades follow the common US scale used in the formula file: A for 90 and up, B for 80 to 89, C for 70 to 79, D for 60 to 69, and F below 60.
- •Results can include decimals when the question count does not divide evenly into 100, so a score like 43 out of 47 becomes 91.49%.
- •Use questions missed, not questions correct, in the second field.
- •This method only fits tests where each question has the same value and no partial credit is awarded.
How to Use
- 1Enter the total number of questions on the test. Use the full count from the quiz or exam, such as 10, 25, 40, or 100.
- 2Enter how many questions were answered wrong. If the paper shows skipped questions counted as wrong, include those too.
- 3Read the percentage result to see the exact test score. The tool also shows the number of correct answers so you can check the paper against the answer key.
- 4Read the letter grade shown with the score. The grade uses the standard 90, 80, 70, and 60 cutoffs rather than plus or minus grading.
- 5If you are planning for a future test, change the wrong-answer count up or down by one question at a time to see how much each mistake affects the final grade.
How It Works
Formula
score % = (total - wrong) / total x 100Start with correct answers = total questions - wrong answers. Then calculate score percentage = correct answers / total questions x 100. In the formula file, the tool accepts only whole-number counts where total questions is at least 1 and wrong answers stays between 0 and the total. After it computes the percentage, it rounds the displayed value to at most 2 decimal places and assigns a letter grade on the fixed 90, 80, 70, 60 scale. For example, 20 total questions and 3 wrong answers gives 17 correct, 17 / 20 = 0.85, and 0.85 x 100 = 85%.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
20 questions, 3 wrong
Missing 3 questions leaves 17 correct answers. Dividing 17 by 20 gives 0.85, so the score is 85%. That lands in the B range on the standard letter scale used by this tool.
50 questions, 8 wrong
Missing 8 questions leaves 42 correct answers. Dividing 42 by 50 gives 0.84, which becomes 84%. This is still a B, but it sits closer to a C than to an A.
25 questions, 1 wrong
Missing 1 question leaves 24 correct answers. Dividing 24 by 25 gives 0.96, so the score is 96%. This example shows that one missed question on a medium-length test often still leaves a strong A.
40 questions, 12 wrong
Missing 12 questions leaves 28 correct answers. Dividing 28 by 40 gives 0.70, so the score is 70%. That lands exactly at the bottom of the C range, so one more wrong answer would drop it to a D.
60 questions, 21 wrong
Missing 21 questions leaves 39 correct answers. Dividing 39 by 60 gives 0.65, which becomes 65%. On the standard scale in the formula logic, 65% is a D.
Grades for a 20 Question Test
A quick lookup table for the most common missed-question counts on a 20-question quiz.
| Wrong answers | Correct answers | Score | Letter 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 |
| 10 | 10 | 50% | F |
Letter grades here assume the common 90, 80, 70, and 60 cutoffs. A school that uses plus and minus grades or a 93% A cutoff may label the same percentage differently.
Common mistakes
- Entering the number correct instead of the number wrong. If you type 17 into the wrong-answer field on a 20-question test, the tool reads that as 17 missed, not 17 correct.
- Forgetting that one mistake matters more on a short quiz. Missing 1 question on a 10-question test drops the score to 90%, while missing 1 on a 50-question test still leaves 98%.
- Assuming every school uses the same letter-grade cutoffs. Some classes require 93% for an A or use A-minus and B-plus bands, but this page uses the fixed 90, 80, 70, 60 scale from the formula logic.
- Using question counts when the teacher grades by points. If one essay is worth 20 points and each multiple-choice item is worth 1 point, grade by total points instead.
- Rounding too early when checking by hand. Work out correct answers first, divide by the total, and then convert to a percentage before rounding the final display.
Embed this calculator on your site
Drop this single line where you want the calculator to appear. It is responsive, mobile-friendly, resizes automatically, and is free to use with attribution.
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