This grade curve calculator rescales a set of grades using linear adjustment, proportional scaling, a bell curve, or square-root curving.
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Grade Curve Calculator
Rescale a set of grades with linear, ratio, bell-curve, or square-root curves.
Calculator
About this calculator
Formula notes
Linear adds a constant or maps the highest score to a target; ratios multiply by H/max; the bell curve uses new = μ + zσ with the population standard deviation; square-root curving uses sqrt(x) × k.
Worked examples
- Example: grades of 80, 70, and 90 with the highest grade raised to 100 become 90, 80, and 100.
- Grades of 80, 70, and 90 rescaled to a 100-point maximum become 90, 80, and 100.
How to use it
- Enter the original grades.
- Choose the curving method and its parameters.
- Read each rescaled grade and compare with the original distribution.
Frequently asked questions
Which curving method should I choose?
Use the one that matches your course policy: fixed points shift everyone equally, proportional scaling preserves ranking, and the bell curve targets a chosen mean and spread.
Can results exceed 100%?
The calculator follows the chosen method exactly; check the rescaled values before publishing them as final grades.
Limits and interpretation
- Curved results depend entirely on the chosen method and parameters; different methods give different rankings for the same input.
- A curved grade is a classroom adjustment and may not follow a school's official grading policy or transcript rules.