Grade Curve Calculator
Enter your raw score to see it adjusted by the three most common curve methods: scaling to the highest score in the class, adding flat bonus points, and the square-root curve. Compare the results side by side.
How to calculate grade curve
A curve adjusts raw scores upward, and teachers use several methods. The top-score method treats the highest score in the class as 100% and scales everyone up by the same ratio. The flat method simply adds a fixed number of points to every score. The square-root curve takes the square root of the raw score and multiplies by 10, which helps lower scores more than higher ones. This calculator shows all three so you can see how each would change your grade.
Top-score = raw / highest x 100; flat = raw + bonus; square-root = sqrt(raw) x 10
Worked example
Your raw score is 80, the top score in the class is 92, and the teacher is considering a 3-point flat bonus.
- Top-score curve: 80 / 92 x 100 = 86.96
- Flat bonus: 80 + 3 = 83
- Square-root curve: sqrt(80) x 10 = 89.44
Result: Depending on the method, your 80 becomes about 87, 83, or 89.
Frequently asked questions
How does a grade curve work?
A curve raises raw scores using a chosen rule. Common methods scale everyone to the top score, add a flat number of points, or apply a square-root formula. The goal is usually to adjust for a hard test so the distribution of grades matches what the teacher expected.
What is a square-root curve?
A square-root curve replaces each raw score with its square root times 10. A 64 becomes 80, and an 81 becomes 90. It boosts lower scores more than higher ones, so it narrows the gap between students while still keeping the order of grades.
What is the top-score (highest-grade) curve?
This method treats the highest score in the class as 100% and scales every other score up by the same proportion. If the top score is 92, everyone's score is divided by 92 and multiplied by 100, so the best paper sets the new ceiling.
Do teachers have to curve grades?
No. Curving is optional and varies by teacher and school. Some curve only when a test was unusually hard, others never curve. This calculator lets you see what a curve would do, but whether one is applied is up to your instructor.