A score out of X is a percentage: divide the points earned by the points possible and multiply by 100. 17 out of 20 is 85% (a B), 12 out of 15 is 80% (a B−), and 42 out of 50 is 84% (a B), on the standard US scale.
Common scores and the grade they earn
The table below converts the scores people look up most often. Each row uses the standard US scale, where an A starts at 93%, a B at 83%, a C at 73% and a pass at 60%.
| Score | Percentage | Letter grade |
|---|---|---|
| 17 out of 20 | 85% | B |
| 12 out of 15 | 80% | B− |
| 8 out of 10 | 80% | B− |
| 19 out of 20 | 95% | A |
| 13 out of 20 | 65% | D |
| 42 out of 50 | 84% | B |
| 23 out of 25 | 92% | A− |
| 18 out of 20 | 90% | A− |
| 14 out of 15 | 93.3% | A |
| 2 out of 3 | 66.7% | D |
| 4 out of 5 | 80% | B− |
| 7 out of 8 | 87.5% | B+ |
How to work out the grade by hand
- Divide the points earned by the points possible: 17 ÷ 20 = 0.85.
- Multiply by 100 to get the percentage: 0.85 × 100 = 85%.
- Match the percentage to your grading scale: on the standard US scale 85% falls in the 83–86% band, a B.
Why the same score can be a different grade
Two classes can give 17 out of 20 different letters. A strict scale starts an A at 95% and a lenient one at 90%, and some schools drop plus and minus grades entirely. If a paper is marked out of a total that includes bonus points, or one question is worth more than the rest, use the grade calculator so the weighting is handled properly.
For a full wrong-answer-to-letter table on a fixed test length, open the grading scale page or the grade chart generator. To check how many you can miss, see how many questions you can miss.