How the grades are worked out
Formula
The calculation is percent = (questions − wrong) ÷ questions × 100 for the result. Right mode uses the right count directly: percent = right ÷ questions × 100 for the result.
Rounding
Whole percentages stay as they are, such as 85%. Every other result is shown to one decimal place and rounded half up, such as 86.7%. The exact score determines the letter grade; the rounded score never does. A score just below a cut-off therefore keeps the lower letter.
Letter grade scales
Every letter begins at the percent shown and continues to the next one. Anything under the lowest cutoff gets an F. Both scales follow the tables on Wikipedia in Academic grading in the United States.
| Letter | From |
|---|---|
| A+ | 97% |
| A | 93% |
| A− | 90% |
| B+ | 87% |
| B | 83% |
| B− | 80% |
| C+ | 77% |
| C | 73% |
| C− | 70% |
| D+ | 67% |
| D | 63% |
| D− | 60% |
| F | below 60% |
| Letter | From |
|---|---|
| A | 90% |
| B | 80% |
| C | 70% |
| D | 60% |
| F | below 60% |
Line for misses
With each letter, it finds the biggest whole number of wrong answers that still gets that letter on the test you entered, based on the scale you chose.
Checked before each release
The same code that runs the calculator works out these scores again for every site build. If any score changes, the build stops.
| Questions | Wrong | Scale | Percent | Grade |
|---|---|---|---|---|
| 20 | 3 | Plus-minus | 85% | B |
| 25 | 4 | Plus-minus | 84% | B |
| 40 | 7 | Plus-minus | 82.5% | B− |
| 30 | 4 | Plus-minus | 86.7% | B |
| 10 | 1 | Plus-minus | 90% | A− |
| 50 | 0 | Plus-minus | 100% | A+ |
| 8 | 1.5 | Plus-minus | 81.3% | B− |
| 20 | 20 | Plus-minus | 0% | F |
| 20 | 2 | Simple A–F | 90% | A |
| 20 | 9 | Simple A–F | 55% | F |