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To grade a test, subtract the number wrong from the total, divide by the total and multiply by 100: missing 7 out of 40 gives 33 ÷ 40 = 82.5%, a B on the standard U.S. scale (A 90–100, B 80–89, C 70–79, D 60–69, F below 60).
This calculator is built for that job. Enter the number of questions and the number missed, and it returns the percentage, the letter grade and the count of correct and wrong answers. It works for any test from 1 to 10,000 questions, which makes it a fast replacement for a paper EZ-grader chart.
What it does not do is combine several assignments into a course grade or tell you what you need on a final exam. Both are explained below with the exact formulas, so you can do them by hand or with the percentage this tool gives you. The letter cutoffs are a common convention, not a national rule; your school or instructor may set them differently.
Grade Calculator: step-by-step worked example
- Total questions
- 40
- Number wrong
- 7
- 1
Correct answers
Correct = Total − Wrong
40 − 7 = 33 questions
- 2
Percentage score
Score = Correct ÷ Total × 100
33 ÷ 40 × 100 = 82.5%
- 3
Letter grade
A ≥ 90 · B ≥ 80 · C ≥ 70 · D ≥ 60 · else F
= B
- 4
Cost of each wrong answer
Per wrong answer = 100 ÷ Total
100 ÷ 40 = 2.5%
- F
- D
- C
- B
- A
Good to know: Uses the standard US scale without plus/minus steps (B+, B−). If some questions carry partial credit, compute the score from total points instead of question count.
Grade Calculator — how it works
What the calculator computes
| Step | Formula |
|---|---|
| Correct answers | total − wrong |
| Percentage | correct ÷ total × 100 |
| Letter grade | A ≥ 90, B ≥ 80, C ≥ 70, D ≥ 60, otherwise F |
The percentage is rounded to two decimals, and the letter is assigned from the unrounded value. There is no rounding up: 89.99% is a B. If your instructor rounds 89.5% to 90%, apply that rule yourself.
Every question counts equally. If a test mixes 1-point and 5-point questions, enter points instead of questions: total points possible as "Total questions" and points lost as "Number wrong".
Letter grades are set by schools, not by law
The 90/80/70/60 scale is the most common U.S. convention, and College Board's GPA guide lists A as 90–100, B as 80–89 and C as 70–79. Its example then uses 66–69 for a D, which already differs from the 60–69 used here. Universities such as UNC-Chapel Hill define grade points for each letter but leave the percentage cutoffs to individual instructors. Check the syllabus before trusting any letter, including this one.
When a course uses plus/minus grades, a common pattern is shown below. Percent bands vary; the grade points are those published by registrars such as UNC and the University of Missouri.
| Letter | Typical percent band | Grade points (4.0 scale) |
|---|---|---|
| A | 93–100 | 4.0 |
| A− | 90–92 | 3.7 |
| B+ | 87–89 | 3.3 |
| B | 83–86 | 3.0 |
| B− | 80–82 | 2.7 |
| C+ | 77–79 | 2.3 |
| C | 73–76 | 2.0 |
| C− | 70–72 | 1.7 |
| D+ | 67–69 | 1.3 |
| D | 60–66 | 1.0 |
| F | below 60 | 0.0 |
Some schools also use A+ (Missouri counts it as 4.0) or D− (0.7).
Quick chart: percentage by number wrong
| Questions | 1 wrong | 2 wrong | 3 wrong | 5 wrong |
|---|---|---|---|---|
| 10 | 90% (A) | 80% (B) | 70% (C) | 50% (F) |
| 20 | 95% (A) | 90% (A) | 85% (B) | 75% (C) |
| 25 | 96% (A) | 92% (A) | 88% (B) | 80% (B) |
| 30 | 96.67% (A) | 93.33% (A) | 90% (A) | 83.33% (B) |
| 50 | 98% (A) | 96% (A) | 94% (A) | 90% (A) |
| 100 | 99% (A) | 98% (A) | 97% (A) | 95% (A) |
Each wrong answer costs 100 ÷ total questions percentage points: 10 points on a 10-question quiz, 4 on a 25-question test, 1 on a 100-question exam. That is why short quizzes produce such jumpy grades, and why many teachers weight them less than unit tests or drop the lowest quiz score. If a test includes partial credit, count half-credit answers as 0.5 wrong; the calculator accepts whole numbers only, so for partial credit switch to points (for example 80 points possible, 9.5 lost becomes 160 and 19 in half-points).
How many can you miss and still get an A?
On a 90% A cutoff, the number you can miss is 10% of the total, rounded down: 2 on a 20-question quiz, 5 on a 50-question test, 10 on a 100-question exam. For a B (80%) the allowance doubles. The fewer the questions, the bigger each mistake: one wrong on a 10-question quiz costs 10 points, on a 50-question test only 2.
Weighted course grades
A course grade is a weighted average of category scores:
course grade = Σ (category score × category weight), with weights as decimals that add up to 1.
If homework (20%) is 92%, quizzes (30%) are 85% and the midterm (50%) is 78%: 92 × 0.20 + 85 × 0.30 + 78 × 0.50 = 18.4 + 25.5 + 39.0 = 82.9%. If weights don't add to 100% yet, because the final hasn't happened, divide by the sum of the weights you do have. Use this calculator for each test's percentage, then combine.
What do I need on the final?
The "final grade" question is the most common grade search, and it has a closed formula:
needed on final = (target − current × (1 − w)) ÷ w
where current is your grade before the final and w is the final's weight as a decimal. With a current grade of 84% and a final worth 25%:
- To finish with 80%: (80 − 84 × 0.75) ÷ 0.25 = (80 − 63) ÷ 0.25 = 68%
- To finish with 85%: (85 − 63) ÷ 0.25 = 88%
- To finish with 90%: (90 − 63) ÷ 0.25 = 108%, so an A is out of reach without extra credit
This assumes your current grade already reflects the other 75% of the course. If some categories are still incomplete, the answer changes.
Points-based and curved grading
Many college courses grade on total points (for example 1,000 points in the term) rather than percentages per category; then your grade is simply points earned ÷ points possible, which this calculator handles if you enter points. Curving is different: an instructor may add a fixed number of points, scale scores so the top score becomes 100%, or assign letters by rank. None of these can be predicted from your raw score alone, so the result here is your raw, uncurved percentage.
Worked example
A high school teacher grades a 40-question chemistry test. One student misses 7.
- Correct answers: 40 − 7 = 33
- Percentage: 33 ÷ 40 × 100 = 82.5%
- Letter: 82.5 is at least 80 and below 90, so B on the standard scale
If the school uses plus/minus bands like those in the table above, 82.5% falls in the 80–82 band, a B−, worth 2.7 grade points instead of 3.0. That is why the same test can show up as a B in one gradebook and a B− in another.
With 40 questions, each question is worth 2.5 points. The student would have needed 36 correct (4 wrong, 90%) for an A, or 3 more right answers. Missing 13 (67.5%) would have dropped the grade to a D.
Now say this test is the midterm, worth 30% of the semester, and the student's other work (70%) averages 88%. The semester grade so far is 88 × 0.70 + 82.5 × 0.30 = 61.6 + 24.75 = 86.35%, a B on the 90/80/70/60 scale.
Frequently asked questions
How do I calculate my grade percentage?+
Divide the number of correct answers (or points earned) by the total and multiply by 100. 33 correct out of 40 is 33 ÷ 40 × 100 = 82.5%.
What letter grade is an 85%?+
On the common 90/80/70/60 scale, 85% is a B. With plus/minus bands it is usually a B (83–86%), worth 3.0 grade points, but your school's cutoffs decide.
What is 17 out of 20 as a grade?+
17 ÷ 20 = 85%, a B on the standard scale. Missing 3 questions on a 20-question quiz costs 15 points because each question is worth 5%.
How many questions can I miss and still get an A?+
With a 90% cutoff, you can miss 10% of the questions, rounded down: 2 of 20, 3 of 30, 5 of 50 or 10 of 100.
How do I calculate what I need on my final exam?+
Use needed = (target − current × (1 − w)) ÷ w, where w is the final's weight. With 84% now and a 25% final, you need 68% to finish at 80% and 88% to finish at 85%.
How do I calculate a weighted grade?+
Multiply each category score by its weight and add them up. Homework 92% at 20%, quizzes 85% at 30% and a midterm 78% at 50% give 18.4 + 25.5 + 39 = 82.9%.
Is a 69.5 rounded to a 70?+
Only if your instructor or school rounds. This calculator does not round up: 69.5% is shown as a D. Many syllabi state whether grades are rounded, so check there.
What is a 3.7 GPA in letter grades?+
3.7 is an A− on the 4.0 plus/minus scale used by registrars such as UNC and the University of Missouri. A plain A is 4.0 and a B+ is 3.3.
Can I use this for tests with different point values per question?+
Yes. Enter the total points possible instead of the number of questions and the points lost instead of the number wrong. The percentage and letter come out the same way.
Sources
About this page
- Publisher:
- Kalkoro — Teknolojig Bilişim Teknolojileri A.Ş., İstanbul
- Written by:
- Kübra Yıldız — Editor (Health, nutrition, pregnancy, education, exam scores)
- Reviewed by:
- Furkan Tur — Editor
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