The Test Grade Calculator works out your percentage score and letter grade from the number of questions on a test and how many you got right or wrong. Enter the total number of questions and either the number correct or the number wrong — the other field fills in automatically.
The test grade calculator turns a raw test result into the two numbers you actually care about: your percentage score and your letter grade. Tell it how many questions were on the test and how many you got wrong — or how many you got right — and it instantly computes the percentage and maps it to a letter grade using a standard grading scale. Whether you are a student checking a quiz, a teacher grading a stack of papers, or a parent helping with homework, it takes the mental arithmetic out of grading and gives an answer you can trust.
It sounds simple, and the math is, but doing it in your head for an odd number of questions — what is 43 out of 50, and is that a B or a B+? — is exactly the kind of small, repetitive task a calculator handles best. This tool does it in one step and shows the full grading scale so you can see where your score falls.
The percentage score is the share of questions you answered correctly, expressed out of 100. The calculator uses whichever count you provide:
percentage score = 100 × (total − wrong) ÷ total
or, equivalently,
percentage score = 100 × correct ÷ total
For example, on a 20-question test with 3 wrong answers, you got 17 right, so your score is 100 × 17 ÷ 20 = 85%. That percentage is then compared against the grading scale to find the corresponding letter grade — in this case, a B. Both forms of the formula give the same answer; the calculator simply lets you enter whichever number you have on hand, since a marked test usually shows the count of mistakes.
Letter grades are assigned by looking up where the percentage falls in a grading scale. This calculator uses the common United States plus/minus (+/−) scale, which divides each letter into three bands:
| Letter Grade | 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% |
This is the scale used by most U.S. high schools and colleges. Note that grading scales vary between institutions — some use a simple letter scale without pluses and minuses, some set different cutoffs, and some use entirely different systems — so always check your school's official policy if the exact letter matters.
When a test comes back, the teacher has usually marked the mistakes, so the fastest thing to count is the number of wrong answers. That is why this calculator defaults to counting wrong answers — you glance at the red marks, count them, and enter the total. But you can just as easily switch to entering the number correct if that is what you have, for instance when a quiz reports a raw score like "18 correct." Either way, the calculator derives the other count and the percentage automatically, so use whichever number is in front of you.
The percentage and the letter grade tell slightly different stories. The percentage is precise and continuous — it captures the exact difference between an 83% and an 86%, even though both are a "B." The letter grade is a coarser summary that schools use for report cards, transcripts, and grade point averages. Because letter grades are what typically get recorded and converted into a GPA, the boundary between two letters can matter a great deal: a single extra correct answer that nudges a 79% up to an 80% turns a C+ into a B−, which can meaningfully change a GPA. Seeing both numbers side by side helps you understand not just how you did, but how close you were to the next band up.
Letter grades are the building blocks of your grade point average (GPA). On the standard 4.0 scale, each letter is worth a number of grade points — an A is 4.0, a B is 3.0, a C is 2.0, and so on, with pluses and minuses adding or subtracting roughly 0.3 (an A− is about 3.7, a B+ about 3.3). Your GPA is the average of these grade points, weighted by the credit hours of each course. So the letter grade this calculator produces is the link between a single test score and your overall academic record. If you want to see how a set of grades combines into a GPA, or what grade you need on a final to reach a target, our GPA Calculator handles that next step.
A percentage is simply a number expressed as a fraction of 100, and a test score is a natural fit: it tells you how many questions out of every hundred you would have gotten right at the same rate. This makes scores comparable across tests of different lengths — 17 out of 20 and 85 out of 100 are both 85%, the same level of performance. It is also why percentages, rather than raw counts, are used to assign grades: a 45-out-of-50 quiz and a 90-out-of-100 exam represent identical mastery, and both earn an A− on the standard scale. Converting to a percentage strips away the arbitrary length of the test and leaves a clean measure of how well you did.
Keep in mind that the percentage depends entirely on the total you enter. Miscounting the number of questions — forgetting a multi-part question, or including a bonus item that should not count toward the base — will shift the percentage and possibly the letter grade. It is worth double-checking the total, since it is the denominator that everything else rests on.
The letter-grade scale used here is standard in the United States, but grading conventions differ widely from country to country. Many nations use numerical scales instead — the United Kingdom uses percentage bands with classifications, much of Europe uses scales such as 1–5 or 1–10 or 1–20, and some systems run "backward," where a lower number is better. Even within the U.S., the plus/minus scale is not universal: some schools use only whole-letter grades (A, B, C, D, F), and the exact percentage cutoffs can vary by a point or two. Because of this variety, a percentage score is the most portable measure — it means the same thing everywhere — while the letter grade always depends on the local scale. This calculator gives you the percentage first, then applies the most common U.S. scale to suggest a letter.
Because the percentage depends on the total number of questions, the same number of mistakes produces very different grades on a short quiz versus a long exam. A few examples make this concrete:
Notice how forgiving a longer test is: on a 100-question exam, each mistake costs only one percentage point, whereas on a 10-question quiz each mistake costs ten. This is why a single careless error feels so much more punishing on a short assessment, and why teachers often use longer tests when they want a grade to reflect overall mastery rather than a single slip.
The calculator shows the percentage to two decimal places and assigns the letter grade from that value. This matters right at the edges of a grading band. A score of exactly 90% is an A−, but 89.99% falls into B+ territory. When a score lands fractionally below a cutoff, some instructors round up as a courtesy and others do not — policies vary. The calculator applies the cutoffs strictly, so if you are hovering just under a boundary, it is worth knowing your teacher's rounding practice. The percentage figure lets you see exactly how far you are from the next grade up, which is more informative than the letter alone.
For educators, the fastest workflow when grading a stack of papers is to count the mistakes on each test rather than the correct answers — you have already marked the errors, so they are right there. Enter the total number of questions once, leave the calculator on "wrong answers," and then you only need to type each student's error count to get their percentage and letter grade. This mirrors the classic paper grading wheels and "EZ Grader" charts that teachers have used for decades, which are simply lookup tables of score versus number wrong. The digital version is faster, handles any test length, and removes the arithmetic mistakes that creep in when grading dozens of papers by hand.
If your test has questions of unequal weight, or includes bonus questions, compute the earned points and the maximum possible points first, then enter those two figures (as correct and total) to get the weighted percentage.
This calculator treats every question as worth the same amount, which is how most quizzes and standardized tests work. Some assessments are different: an essay might be worth 20 points while each multiple-choice question is worth 2, or a test might include extra-credit items that can push a score above 100%. To handle a weighted test, add up the points a student earned and divide by the total points available — enter those as the correct count and the total. Extra credit can produce a percentage above 100%, which simply means a score better than a perfect base test; on most scales anything at or above the top cutoff is still the highest grade. The key is to make sure the "total" you enter reflects how the test is actually scored.
Letter grades are a surprisingly recent invention. For much of the history of education, students were ranked or described in narrative reports rather than given a single mark. The A–F system familiar in the United States emerged in the late nineteenth and early twentieth centuries as schools grew and needed a standardized, compact way to report achievement. The percentage-to-letter mapping — roughly 90s for an A, 80s for a B, and so on — became the dominant convention, and the finer plus/minus gradations were added later to distinguish performance within each band. Today the letter grade remains the standard currency of academic achievement in American schools, even as debates continue about whether it truly captures learning. Whatever its merits, converting a raw score to a letter is a task every student and teacher faces constantly, and this calculator handles it in a click.
Divide the number of correct answers by the total number of questions and multiply by 100 to get the percentage. Then look that percentage up on a grading scale to find the letter grade. The calculator above does both steps for you.
15 out of 20 is 75%, which is a C on the standard plus/minus scale. Enter 20 as the total and either 5 wrong or 15 correct to confirm.
On the standard scale, an A is 93–96%, an A+ is 97–100%, and an A− is 90–92%. So any score of 90% or above earns some form of an A.
Either works. The calculator defaults to wrong answers because marked tests usually show the mistakes, but you can switch to entering correct answers if that is the number you have. The result is identical.
Yes. Enter any total — 10, 25, 40, 100, or any other number — and the calculator computes the percentage and letter grade. It handles tests of any length.
No. This calculator uses the common U.S. plus/minus scale, but schools and countries use different scales and cutoffs. Use the percentage as the universal measure and check your institution's policy for the exact letter grade.
This Test Grade Calculator is provided for educational and general informational purposes. It computes a percentage score and applies a common grading scale to suggest a letter grade; your school or instructor may use different cutoffs, weighting, or grading systems. Always refer to your official grading policy for definitive grades.