Grade curve calculator
For teachers adjusting a hard test: enter the top score in the class, the maximum score and a student score.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter top score in class, maximum score and student score.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Flat: score + (maximum − top). Proportional: score × maximum ÷ top. Square root: √(score ÷ maximum) × maximum.
Example
Inputs: Top score in class = 88, Maximum score = 100, Student score = 72. Result: Flat curve: 84; Proportional curve: 81.82; Square root curve: 84.85.
Limits and caveats
- These are common adjustments, not an official rule; the teacher or school decides which to use.
- It does not apply a bell curve, which needs the whole class distribution.
Questions about this tool
Which method should I use?
Flat lifts everyone equally, proportional rewards high scores more, and the square root curve lifts low scores more.
Can a curved score go above the maximum?
Not with these three methods, as long as the student score is not above the top score.
What is the square root curve?
On a 100 point test it is 10 × √score, so 64 becomes 80.