Curve grade calculator
Choose how your instructor curves the exam, enter the raw score and the numbers that method needs, and see the curved score, its percentage and how many points it moved. Every curved score is kept between zero and the maximum.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Pick the curving method.
- Enter your raw score and the maximum score.
- Fill in the extra number the method needs: the points to add, the top score, or the class mean and standard deviation with your targets.
- Read the curved score, the percentage and the change.
How it works
- Add points: score + points, capped at the maximum.
- Lift the top score: score + (maximum − highest score).
- Square root: maximum × √(score ÷ maximum).
- Bell curve: target mean + (score − class mean) ÷ class SD × target SD.
Results are never below 0 or above the maximum.
Worked example
A raw 72 out of 100 with a class mean of 65 and a standard deviation of 12 has z = (72 − 65) ÷ 12 = 0.58. With a target mean of 75 and target SD of 10 the curved score is 75 + 0.58 × 10 = 80.8.
Tips
A curve can lower a score only with the bell method, when your score is below the class mean and the target is stricter than the class. Check your syllabus for the exact method before relying on any estimate.
Frequently asked questions
How does the square root curve work?
The curved score is the maximum times the square root of (score ÷ maximum). On a 100-point test that is 10 × √score, so 72 becomes about 84.9. Low scores gain the most and a perfect score stays perfect.
What is the flat curve to the top score?
It adds the gap between the maximum and the best score in the class to everyone. If the top score is 91 out of 100, every score goes up by 9, so the best paper becomes 100.
How does a bell curve change my score?
It converts your score to a z-score, (score − class mean) ÷ class standard deviation, and places it on a new scale with the target mean and spread. A score one standard deviation above the class mean lands one target deviation above the target mean.
Will my instructor use the same method?
Not necessarily. Instructors curve in many ways, and some do not curve at all. This tool shows the result of each common method so you can compare; the instructor's own method decides your real grade.