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.
Passing-grade examples by test length
The table shows the most questions a student can miss while still meeting common 60%, 70%, and 80% cutoffs. It assumes equal-value questions and no partial credit.
| Total questions | Miss for 60% | Miss for 70% | Miss for 80% |
|---|---|---|---|
| 10 | 4 | 3 | 2 |
| 20 | 8 | 6 | 4 |
| 25 | 10 | 7 | 5 |
| 50 | 20 | 15 | 10 |
| 100 | 40 | 30 | 20 |
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.
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.
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.
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.
Grade Calculator Editorial Team
We create plain-language grading tools and educational guides, check every worked example against the underlying formula, and note where school or instructor policies can change the result.