Grade Curve Calculator
Apply a flat, linear-scale, or square-root curve to a raw score.
Raw 64 → curved 80 (+16 points).
Curving raises raw scores using a rule the instructor picks. The square-root curve is curved = √raw × 10: a raw 64 becomes √64 × 10 = 8 × 10 = 80. A flat curve adds fixed points; a linear scale multiplies by 100 ÷ the top score. Every curved score is capped at 100.
What curving does
A curve is a formula an instructor applies to every raw score so the class average or the top score lands where they want it. It does not change how many questions you answered — it remaps the raw number to a higher curved number. The three common methods differ in who benefits most.
Flat (add points). Every student gains the same number of points. A frequent choice sets that bonus so the highest score in the class becomes 100 — the bonus is 100 − highest score. It shifts everyone up equally.
Linear scale. Every score is multiplied by 100 ÷ the highest score, so the top paper becomes exactly 100 and everything below scales in proportion. Lower scores rise, but by a smaller number of points than the top.
Square root. The curved score is √raw × 10 on a 0–100 scale. Because a square root grows fastest near zero, this method boosts low scores the most and barely touches scores already near 100.
Linear: curved = raw × 100 ÷ top · Flat: curved = raw + (100 − top)
Worked example
A raw score of 64, square-root curve.
- 1 Pick the curve method. Here, the square-root curve: curved = √raw × 10.
- 2 Take the square root of the raw score. √64 = 8.
- 3 Multiply by 10. 8 × 10 = 80.
- 4 Cap at 100. 80 is below 100, so the curved score is 80 — a B−.
Same raw score under each method
A raw score of 64 with a class-high of 88; the square-root curve lifts it most.
| Method | Formula with numbers | Curved score |
|---|---|---|
| Flat (add points) | 64 + (100 − 88) = 64 + 12 | 76 |
| Linear scale | 64 × 100 ÷ 88 | 72.7 |
| Square root | √64 × 10 | 80 |
Reading the results
Every method raises scores — none can lower a raw score below what you earned. Which one helps you most depends on where you sit: the square-root curve gives the biggest lift to low scores and almost none to scores near 100, so it compresses the class toward the top.
Flat and linear preserve rank. Adding the same points, or multiplying by the same factor, keeps everyone in the same order they started. The square-root curve also keeps the order, but it narrows the gaps between students.
The curve is the instructor’s call. These formulas show what each method would give — your teacher decides whether a curve is applied and which one. Compute your raw percentage first, then apply the announced curve.