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Grade Curve Calculator

Calculate your curved grade using flat, square root, or bell curve methods. Enter your raw score and curve settings to see your adjusted grade.

Your original score before the curve

Maximum points possible on the assignment

Select the type of curve to apply

For flat curve: percentage points to add. For bell curve: current class average percentage. Ignored for square root curve.

What is a Grade Curve Calculator?

The Grade Curve Calculator helps you determine your curved grade using three popular curving methods. A flat curve adds a fixed percentage to all scores. A square root curve applies the formula new% = sqrt(old%) x 10, which benefits lower scores more than higher ones. A bell curve shifts all scores so the class average reaches a target (typically 75%). Grade curving is commonly used by professors when an exam is harder than intended or when the class average is lower than expected. Enter your raw score, total points, and preferred curve method to see your adjusted grade.

Formula

Flat: scorenew=scoreraw+(total×curve%100)\text{Flat: } score_{new} = score_{raw} + (total \times \frac{curve\%}{100})

The flat curve adds a fixed percentage of total points. The square root curve uses new% = √(old%) × 10. The bell curve shifts scores to reach a target class average of 75%.

How to Calculate

  1. 1

    Enter your raw score on the assignment or exam.

  2. 2

    Enter the total points possible.

  3. 3

    Select a curve method: Flat (adds fixed points), Square Root (benefits lower scores more), or Bell Curve (shifts to target average).

  4. 4

    Enter the curve amount: for flat curves, enter the percentage to add; for bell curve, enter the current class average percentage. This field is ignored for square root curves.

  5. 5

    Click Calculate to see your curved score, curved percentage, and letter grade.

Worked Examples

Flat Curve — Adding 10%

Input: Raw: 72/100, Curve Type: Flat, Curve Amount: 10%

  1. Raw percentage: 72/100 = 72%
  2. Curve: add 10% of 100 = 10 points
  3. Curved score: 72 + 10 = 82/100 = 82%
  4. Letter grade: B-

Result: Curved Score: 82, Curved Percentage: 82%, Letter Grade: B-

Square Root Curve

Input: Raw: 64/100, Curve Type: Square Root

  1. Raw percentage: 64/100 = 64%
  2. Apply square root: √64 × 10 = 8 × 10 = 80%
  3. Curved score: 80/100
  4. Letter grade: B-

Result: Curved Score: 80, Curved Percentage: 80%, Letter Grade: B-

Bell Curve — Class Average 55%

Input: Raw: 60/100, Curve Type: Bell Curve, Class Average: 55%

  1. Current class average: 55%
  2. Target average: 75%
  3. Shift: +20 percentage points
  4. Curved score: 60 + 20 = 80/100 = 80%
  5. Letter grade: B-

Result: Curved Score: 80, Curved Percentage: 80%, Letter Grade: B-

Frequently Asked Questions

It depends on the situation. Flat curves are simplest and treat everyone equally. Square root curves help lower-performing students more. Bell curves normalize scores to a target average. Your professor's choice usually depends on the score distribution.
The square root curve takes the square root of your percentage score and multiplies by 10. For example, a 49% becomes √49 × 10 = 70%. This method gives a bigger boost to lower scores than higher ones.
A flat curve only adds points, so it cannot lower your grade. A square root curve always increases scores below 100%. A bell curve could theoretically lower scores if the class average is already above the target (75%).
A bell curve shifts all scores so the class average hits a target, usually around 75% (C). If the class average was 55%, everyone gets +20 percentage points added to their score.
No, curving is at the professor's discretion. Some departments or universities have policies about curving. It's most common in STEM courses where exam averages tend to be lower.

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