Grade Curve Calculator
A test that was harder than intended should not sink the whole class. Paste the raw scores, pick a curve method — square root, flat addition or bell curve — and see every adjusted score with before-and-after class statistics.
Used only with Flat addition.
Used only with Bell curve.
Curved scores
| # | Original | Curved | Grade | Change |
|---|
Class statistics
| Before | After |
|---|
Grades use a standard scale: A 90+, B 80+, C 70+, D 60+, F below 60 (percent of maximum points).
How to use
- Paste the raw scores and set the maximum points of the test.
- Choose a curve method: square root (helps low scores most), flat addition (same points for everyone), or bell curve (reshapes scores around a target average).
- Results update instantly as you type or change the method.
Note: A curve should make grading fairer, not just higher — use it when a test turned out harder than intended, and explain the method to your students. Curved scores can never exceed the maximum points. All calculations happen in your browser.
Tips
- Curve to fix an unfair test, not to manufacture grades — explain the method to students so it stays transparent.
- Square root curves help low scores most; flat addition treats every student equally.
- Curved scores never exceed the maximum points — the tool caps them automatically.
- Compare the before and after averages; if the curve barely moved anything, the test was probably fine.