Grade Curve Calculator

A grade curve adjusts a set of raw scores so the final grades better reflect the difficulty of an assessment or a target distribution. Paste the raw scores, set the maximum possible score, pick a method, and the calculator recomputes every score, then compares the original and curved distributions along with mean, median, spread, and pass rate.

Curve methods

• Square root curve. Each score is replaced by √(percentage) × max. Low scores rise the most and high scores barely move, which gently lifts a class after a hard test. A 49% becomes 70%, while a 90% stays near 95%.
• Linear shift (add points). A fixed number of points is added to every score. Everyone moves up by the same amount; the shape of the distribution is unchanged.
• Linear shift (bump top to max). The gap between the highest score and the maximum is added to everyone, so the top student reaches full marks and the rest rise by the same offset.
• Bell curve. Scores are rescaled so the class hits a chosen mean and standard deviation, using (score − mean) ÷ std × targetStd + targetMean. This standardises the spread rather than just shifting it.
• Drop lowest N scores. The lowest N values are removed from the set before statistics are recomputed, useful when the collection represents repeated attempts or quiz drops.

Optionally cap curved scores at the maximum and floor them at zero so no adjusted grade lands outside a valid range. All calculations happen locally in your browser; no scores are ever sent to a server.

You can embed this util on your own site as a widget. Adding ?embed=1 to the URL loads a compact version with just the tool itself; no header, menu, or documentation. Paste this snippet into your HTML:

Copy snippet Adjust the height to taste.