Grade Curve Calculator (Curve Test Scores)
Enter your score, the highest score in the class and the curve method to see your curved grade.
Your numbers
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Grade Curve Calculator (Curve Test Scores) by TheCalcTools
How the Grade Curve Calculator (Curve Test Scores) works
A flat curve adds the same points to everyone, equal to the gap between the top score and 100. A proportional curve multiplies every score by 100 ÷ top score, helping high scorers a little more.
The square-root curve takes 10 × √score. It helps low scores most (36 becomes 60) and leaves 100 at 100. Teachers choose their own method, if any.
The formula
Worked example
Using the default values shown in the calculator:
| Your score (%) | 68 |
|---|---|
| Highest score in the class (%) | 88 |
| Curve method | Flat: add points so the top score is 100 |
- Score 68 with a top score of 88: the flat curve adds 12 to give 80.0% (B).
- Proportional: 77.3%; square root: 82.5%.
Result:
| Curved score | 80.0% |
|---|---|
| Points added | 12.0 |
| Curved letter grade | B |
| Flat curve | 80.0% |
| Proportional curve | 77.3% |
| Square-root curve | 82.5% |
Frequently asked questions
Is a curve always fair?
It corrects for an unusually hard test, but it is a choice made by the teacher. Some courses never curve.
Does a curve lower anyone's grade?
None of these three methods lowers a score; bell-curve grading by fixed proportions can.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.