How a test score is calculated
A test percentage is the number of questions you got right divided by the number of questions, times 100. If you know how many you missed, subtract that from the total first. On a 25-question test, every question is worth 4 percentage points, so each one missed costs you 4%.
The fewer questions on a test, the more each one matters. Missing one question on a 10-question quiz costs 10 points, a whole letter grade, while missing one on a 50-question exam costs only 2. The grade chart under the result shows every possible score for your test length, which is handy for teachers grading a stack of papers too.
Turning the percentage into a letter grade
The most common US scale is the 10-point scale: 90-100 is an A, 80-89 a B, 70-79 a C, 60-69 a D and below 60 an F. Florida, for example, sets exactly this scale in state law for high school grades. Many schools and colleges add plus and minus grades, often with an A at 93 and up, A- from 90, B+ from 87 and so on.
Schools and teachers set their own scales, and some round (an 89.5 becomes a 90) while others don't. Switch the scale setting to match yours, and check the syllabus when a score sits right on a cutoff.
Partial credit and point-based tests
If questions are worth different amounts, think in points instead of questions: enter the total points on the test and the points you lost. Half credit works too; enter 2.5 wrong for two misses and one half-credit answer. The chart still lists whole questions only.
The test grade formula
Score % = (total − wrong) ÷ total × 100Each question = 100 ÷ total- total = number of questions (or points) on the test
- wrong = questions missed (or points lost)
Example
- A 25-question test with 3 wrong.
- Right answers: 25 − 3 = 22.
- Score = 22 ÷ 25 × 100 = 88%, which is a B on the 10-point scale (a B+ on the plus/minus scale).
- Each question is worth 100 ÷ 25 = 4 points, so missing one fewer would have given 92%, an A.
Frequently asked questions
How many questions can I miss and still get an A?
On the 10-point scale you need 90%. On a 20-question test that's up to 2 wrong (90%); on a 25-question test, 2 wrong (92%) since 3 wrong drops you to 88%; on a 50-question test, up to 5 wrong (90%).
What is 17 out of 20 as a percentage?
17 ÷ 20 × 100 = 85%, a B on the 10-point scale.
What grade is an 88%?
A B on the 10-point scale, and a B+ on most plus/minus scales.
How do I grade a test with different point values?
Add up the points earned and divide by the total points possible. Enter total points as the number of questions and points lost as the number wrong.
Is a 70% passing?
On the 10-point scale, 70% is a C, and 60% is the lowest D. Whether a D counts as passing depends on the school and course; some courses require a C or better to count toward a major or as a prerequisite.
Sources
Last reviewed for 2026. How we calculate.