Compare Added-Point, Scale-to-100, Square-Root and Bell-Curve Grades
Select the curve method, enter the student and class statistics, and see the transformed score, letter grade and movement from the original.
CURVE
Class and score inputs
Curved grade result
How the grade curve calculator works
The add-points method shifts every score by the same number. Scale-to-100 multiplies scores by 100 divided by the highest observed score. The square-root method uses ten times the square root of the original percentage, which raises lower scores more strongly.
Bell-curve transformation
The z-score method first measures how many standard deviations the student is above or below the original class mean. It then places that same relative standing into a target distribution using the target mean and target standard deviation. This preserves rank but changes the scale.
Can a curved score exceed 100?
The calculator caps the reported classroom percentage at 100. The uncapped transformation is still shown in the detail when relevant.
Is grading on a curve always fair?
No. A curve can help normalize an unusually difficult assessment, but it can also hide flawed questions or create artificial competition. Use a documented academic policy.
For U.S. classrooms, publish the chosen method before applying it whenever possible. A curve should not conceal the original score, and district, college or instructor policies may prohibit particular transformations.