Grade Curve Calculator
Paste the class's scores (or just yours), pick a curving method and see every new score, letter and the class average before and after.
Scores & method
New = 10 × √old. Lifts low scores most; 100 stays 100.
Every score, curved
| Original | Curved | Change | Letter |
|---|---|---|---|
| 58 (F) | 76.2 | +18.2 | C |
| 64 (D) | 80 | +16 | B- |
| 67 (D+) | 81.9 | +14.9 | B- |
| 71 (C-) | 84.3 | +13.3 | B |
| 72 (C-) | 84.9 | +12.9 | B |
| 75 (C) | 86.6 | +11.6 | B |
| 78 (C+) | 88.3 | +10.3 | B+ |
| 80 (B-) | 89.4 | +9.4 | B+ |
| 83 (B) | 91.1 | +8.1 | A- |
| 86 (B) | 92.7 | +6.7 | A- |
| 88 (B+) | 93.8 | +5.8 | A |
| 91 (A-) | 95.4 | +4.4 | A |
Which curve is fairest?
A flat or top-to-100 curve helps everyone equally in points. A proportional curve gives the strongest students the most points. The square-root curve does the opposite: a 49 jumps 21 points to 70, while a 90 gains only 4.9. Try each method on the same scores above and watch the letter distribution shift.
| Score | Square root | Top to 100 (high 90) | Proportional (high 90) |
|---|---|---|---|
| 49 | 70 | 59 | 54.4 |
| 60 | 77.5 | 70 | 66.7 |
| 70 | 83.7 | 80 | 77.8 |
| 80 | 89.4 | 90 | 88.9 |
| 90 | 94.9 | 100 | 100 |
After the curve, update your class grade in the grade calculator or work out a single test in the test grade calculator.
Questions students ask
How do teachers curve grades?
The four most common methods are: add the same points to everyone (flat curve), add enough so the top score becomes 100, multiply everyone so the top score becomes 100 (proportional), and the square-root curve (10 × √score). Some teachers instead shift scores so the class average hits a target such as 75%.
What is the square root curve?
Each new score is 10 × √(old score). A 64 becomes 80, an 81 becomes 90 and a 100 stays 100. It helps low scores most and never pushes anyone over 100.
Does a curve always help me?
The methods here only raise scores. A true bell curve (grading on a fixed distribution of A's, B's and C's) can lower a grade in a strong class, which is why many schools avoid it.
Can I curve just my own score?
Yes. Enter only your score and, if you know it, the class high score. For the "average" method you need the class average.