To find how many questions you can miss, multiply the total questions by the required passing percentage, round the required correct answers up to a whole question, and subtract that number from the total. On a 20-question test with a 70% passing score, you need 14 correct and can miss 6.
The maximum-missed-questions formula
A test grade is the percentage of available points earned. When every question has the same value, the number of correct answers can stand in for earned points. The key is to round the required correct answers up, because a fraction of a question usually cannot be answered correctly.
Use this formula: required correct answers = ceiling(total questions × passing percentage ÷ 100). Then calculate maximum wrong answers = total questions − required correct answers.
- Convert the passing grade to a decimal: 70% becomes 0.70.
- Multiply the decimal by the number of questions.
- Round the required correct answers up to the next whole question.
- Subtract required correct answers from total questions.
How many questions can you miss on a 25-question test?
On a 25-question test, you can miss 5 questions and still get 80%, 7 and still get 70%, and 10 and still get 60%. Each question is worth 4 percentage points (100 ÷ 25), so every wrong answer drops the score by exactly 4. That's why 25-question tests land on clean numbers like 80% and 76% instead of long decimals.
The one catch is the A. Getting 90% would take 22.5 correct answers, and half a question isn't possible, so you need 23 correct, which is a 92%. That means 2 wrong is the limit for an A, not 3. Missing 3 leaves you at 88%. The full score-by-score table is on the grading scale for 25 questions page.
| Target grade | Correct needed (of 25) | Most you can miss | Your actual score |
|---|---|---|---|
| 90% (A−) | 23 | 2 | 92% |
| 85% | 22 | 3 | 88% |
| 80% (B−) | 20 | 5 | 80% |
| 75% | 19 | 6 | 76% |
| 70% (C−) | 18 | 7 | 72% |
| 65% | 17 | 8 | 68% |
| 60% (D−) | 15 | 10 | 60% |
How many can you miss by test length and passing score?
The table shows the most questions you can miss while still meeting the five most common cutoffs, from a 60% pass to a 90% A. It assumes equal-value questions and no partial credit, and every number already includes the round-up rule. So the 75% column on a 30-question test says 7, not 7.5.
Read across your test length to see how much room you have at each grade, or down a column to see how the allowance grows with longer tests. For a printable version of these cutoffs, the printable grading scale has the minimum correct answers for each letter.
| Total questions | Miss for 60% | Miss for 70% | Miss for 75% | Miss for 80% | Miss for 90% |
|---|---|---|---|---|---|
| 10 | 4 | 3 | 2 | 2 | 1 |
| 15 | 6 | 4 | 3 | 3 | 1 |
| 20 | 8 | 6 | 5 | 4 | 2 |
| 25 | 10 | 7 | 6 | 5 | 2 |
| 30 | 12 | 9 | 7 | 6 | 3 |
| 40 | 16 | 12 | 10 | 8 | 4 |
| 50 | 20 | 15 | 12 | 10 | 5 |
| 100 | 40 | 30 | 25 | 20 | 10 |
Why the answer changes on shorter tests
Each question carries more weight on a short quiz. On a 10-question quiz, one wrong answer reduces the score by 10 percentage points. On a 100-question exam, one wrong answer reduces it by only 1 percentage point. That is why a grade chart is useful: it makes every possible raw score visible before grading begins.
For a 15-question quiz, 10 correct is 66.67% and 11 correct is 73.33%. There is no whole-question score between those percentages. A 70% passing rule therefore requires 11 correct answers, so the student can miss 4. Short quizzes are also where the 75% and 80% columns collapse together. On a 10-question quiz both allow only 2 misses, because 7.5 correct rounds up to 8.
A quick mental-math shortcut
You can estimate your allowance without a calculator by turning the passing score into a "miss 1 in N" rule. At 80% you can miss 1 in every 5 questions, at 70% 3 in every 10, at 75% 1 in every 4, and at 60% 2 in every 5. On a 40-question test at 80%, that's 40 ÷ 5 = 8 misses.
The shortcut is exact whenever the test length divides evenly. When it doesn't, round your allowance down, which is the same thing as rounding the required correct answers up. A 30-question test at 75% gives 30 ÷ 4 = 7.5, so the real limit is 7. Treat the number as a ceiling, not a target. Missing exactly the maximum leaves no margin for a question you thought you got right.
What if questions have different point values?
Do not count questions when an assessment uses a rubric, essay points, or problems with different weights. Add the points earned instead. Divide earned points by total possible points, then multiply by 100. A student may miss one 10-point problem and lose more than a student who misses several 1-point questions. The percentage of correct answers guide shows how far a question count and a points total can drift apart.
Partial credit also changes the calculation. If a 20-point assignment awards half points, 14.5 points is 72.5%. Use the grade calculator's half- or quarter-point setting rather than a whole-question chart.
What if wrong answers lose points?
On a test with a guessing penalty (negative marking), a wrong answer costs more than a blank one, so the question isn't just how many you can miss but how many you can afford to answer wrongly. The score becomes correct answers minus the penalty times wrong answers. With a quarter-point penalty on a 50-question test, 40 right and 10 wrong gives 40 − 2.5 = 37.5, or 75%, instead of 80%.
Most classroom tests don't use a penalty, and the SAT dropped its quarter-point deduction in March 2016, so on a normal quiz a blank and a wrong answer count the same. If your test does use one, leaving a question blank is safer than a random guess.
Check the actual passing policy
Passing thresholds are not universal. A course syllabus may define 60%, 65%, 70%, or another score as passing, and some programs require a minimum grade in specific assessments. Rounding rules matter near the boundary, too. Confirm whether the instructor rounds the final percentage before deciding that a score passes.
And remember that one test is usually only part of your course grade. Passing a test with room to spare matters less than what that test is worth in the gradebook. How much one assignment is worth shows how to size its effect, and the final grade calculator works out what you need on what's left.
Frequently Asked Questions
How many questions can you miss on a 25-question test and still get an 80?+
You can miss 5. You need 20 correct answers out of 25 for 80%, and 25 − 20 = 5. Each question on a 25-question test is worth 4 percentage points.
How many questions can you miss on a 20-question test?+
You can miss 8 and still get 60%, 6 for 70%, 4 for 80%, and 2 for 90%. Each question on a 20-question test is worth 5 percentage points.
How many questions can you miss and still get an A?+
You can miss 10% of the questions on a 10-point scale, rounded down: 1 on a 10- or 15-question test, 2 on a 20- or 25-question test, 3 on a 30-question test, and 5 on a 50-question test. If your A starts at 93%, the allowance is smaller.
How many questions can you miss on a 50-question test?+
On a 50-question test you can miss 20 and still get 60%, 15 for 70%, 10 for 80%, and 5 for 90%. Each question is worth 2 percentage points.
How many questions can you miss on a 10-question quiz?+
You can miss 4 and still get 60%, 3 for 70%, 2 for 80%, and 1 for 90%. On a quiz this short, every question is worth 10 percentage points.
Why do you round the correct answers up instead of down?+
Because you can't answer a fraction of a question. If a 70% pass on a 15-question quiz needs 10.5 correct answers, 10 correct falls short at 66.7%, so you need 11. Rounding the correct answers up is the same as rounding the misses down.
Is it 60% or 70% to pass a test?+
It depends on the class. Most US high schools set the passing line at 60%, but many college courses, professional programs and some districts require 65% or 70%. Your syllabus states the exact cutoff.
What if my test has 23 or 37 questions?+
Use the formula: multiply the total by the passing percentage, round up, and subtract from the total. For a 70% pass on 37 questions, 37 × 0.7 = 25.9, which rounds up to 26 correct, so you can miss 11. A grade chart for your exact test length shows every score.
Do blank answers count as wrong?+
On most classroom tests, yes. A blank earns no points but still counts in the total, so it uses up one of your allowed misses exactly like a wrong answer.
Does missing questions on one test fail the class?+
Not by itself. A single test is usually one weighted part of the course grade, so passing the class depends on your other grades and how much this test is worth. Check the syllabus weights before worrying about one score.
How many questions can I miss to get a B?+
At an 80% B cutoff, you can miss 20% of the questions, rounded down: 2 on a 10-question quiz, 4 on 20 questions, 5 on 25, 6 on 30, and 10 on 50. Plus/minus scales make 80–82% a B−.
Muhammd Salman
I build and maintain Grade Calculator independently. Every worked example on this site is checked against the underlying formula, with notes on where school or instructor policy can change the result. More about this site →