Curve an exam score with a square-root or linear method, then compare the point gain, percentage change, and optional max-score cap. Use it to test different inputs quickly, compare outcomes, and understand the main factors behind the result before moving on to related tools or deeper guidance.
Last updated
Compare two common ways to curve an exam score Choose a curve method, enter the original score, and see the curved score, point gain, and percentage impact before applying the policy to a full class.
Curve method
Common when instructors want lower scores to gain relatively more than top scores.
Enter a score and choose a curve method Add the original score and the exam maximum first. Linear shift also needs the point adjustment value.
Grade curve calculator guide: square-root and linear curving methods
A grade curve calculator estimates how an exam score changes after a curving policy is applied. This page compares two common methods: a square-root curve and a fixed linear shift, then shows the point and percentage impact before you apply the rule to a whole class.
What a grade curve is doing
A curve changes raw scores after an exam or assignment to reflect instructor policy. Sometimes the goal is to raise overall performance after a difficult assessment. In other cases the goal is to preserve rank order while compressing the spread between lower and higher scores.
The key detail is that different curves behave differently. A square-root curve gives relatively larger boosts to lower raw scores, while a linear shift adds the same number of points to everyone. That is why this page keeps the method explicit instead of folding everything into one generic adjustment.
Square-root curve
The square-root method starts with the ratio of the score to the exam maximum, takes the square root of that ratio, and then rescales it back to the exam maximum. Because square roots flatten lower values more than higher ones, this method tends to help lower raw scores proportionally more.
For example, a raw score of 64 out of 100 becomes 80 after the square-root curve, because sqrt(64 / 100) × 100 = 80. A perfect score remains unchanged.
Curved score = sqrt(score / max score) x max score
Common classroom curving method that preserves the exam maximum while compressing lower scores upward.
Linear shift
A linear shift simply adds a fixed number of points to every score. If the instructor adds 10 points, a 70 becomes 80 and an 88 becomes 98. This preserves the spacing between students because the same adjustment applies to all scores.
Some instructors cap the result at the exam maximum. If a student has 95 out of 100 and the shift is +10, the uncapped result would be 105. A capped policy would stop that score at 100 instead.
Curved score = score + shift points
Fixed-point curve that preserves the distance between students unless a max-score cap is applied.
Worked example
Suppose a student scores 64 out of 100. On a square-root curve, the curved result is 80, which is a 16-point gain and a move from 64% to 80%. On a linear shift of +10 points, that same score becomes 74 out of 100, which is a 10-point gain and a move from 64% to 74%.
Those two results are both legitimate curves, but they serve different classroom goals. The square-root method changes the distribution more aggressively, while the linear shift keeps the structure of the raw score distribution more intact.
Limits of any single-score curve calculator
A full class curve policy may depend on the entire distribution of scores, median performance, or a target class average. This page does not model the whole class distribution. It shows how a single entered score would change under the selected rule.
If your syllabus or instructor publishes a specific policy, use those written rules. The calculator is best used as a planning and interpretation tool, not as a substitute for the official grading policy of a course.
Frequently asked questions
Does a grade curve always help every student equally?
No. A linear shift gives the same point increase to everyone, but a square-root curve changes lower scores proportionally more than higher scores. Different policies can produce very different outcomes from the same raw score.
Why can a linear curve go above 100?
Adding a fixed number of points can push a high raw score past the exam maximum. Some instructors allow that, while others cap the result at the test maximum. This calculator lets you model the capped version explicitly.
Is the square-root curve the same as grading on a bell curve?
No. A square-root curve is a direct mathematical transformation of the raw score. A bell-curve policy usually depends on the class distribution, percentiles, or standard deviations across the full set of scores.
Can I use this to predict my final class grade?
Only cautiously. This page estimates how one assessment score changes under the selected curve method. Your final class grade may also depend on weights, category averages, dropped assignments, and other syllabus rules.
