Grade Curve Calculator

1. Enter your raw score as a percentage.
2. Choose the curve method your instructor uses.
3. For the highest-score curve, add the class highest score; for a flat curve, the points added.
4. Read your curved score, the points gained and the letter grade.

Here is what each result means:

A grade curve is an adjustment an instructor applies to raw scores, usually to raise them when a test was hard. Curving can lift a whole class, close the gap to a top score, or reshape the distribution so grades land where the instructor expects.

There is no single curve. Some instructors add a flat number of points, some set the highest score to 100 and shift everyone up, and some apply a square-root curve that helps lower scores more than high ones. This tool models the common methods so you can see the effect on your score.

It applies the method you pick to your raw score.

1. The highest-score curve adds the gap between the top score and 100 to everyone.
2. The square-root curve replaces the score with ten times its square root, which lifts low scores most.
3. The flat curve adds a set number of points to every score.

To find the raw score you would need before a curve, use the final grade calculator.

Suppose your raw score is 78 and the class high is 88.

Highest-score curve: everyone gains 100 - 88 = 12 points, so your 78 becomes 90, an A-minus. Square-root curve: 10 x sqrt(78) = 88.3. Flat plus 7: 78 + 7 = 85. The method changes the result a lot, so it helps to know which one your instructor uses.

Curves differ in who they help most.

The square-root curve helps low scores the most; the highest-score curve adds the same points to everyone.

Each method suits a different goal.

Instructors pick based on the score spread and the grade distribution they want.

The Method

The biggest factor. The same raw score can gain very different amounts under each curve.

The Class High

For the highest-score curve, a lower top score means a bigger boost for everyone.

The Score Spread

Square-root curves reshape a wide spread, helping the bottom more than the top.

After a Hard Exam

See how a likely curve would change your grade.

Comparing Methods

Check which curve helps your score most so you know what to hope for.

As an Instructor

Test how a curve would shift scores before applying it to the class.

1. Assuming Every Class Is Curved

Many are not. Curving is at the instructor discretion.

2. Using the Wrong Method

Applying a square-root curve when your class uses a flat one gives the wrong result.

3. Expecting a Curve to Fix a Low Score

Most curves add modest points; they rarely turn a failing raw score into an A.

4. Curving Above 100

Most policies cap scores at 100, which this tool applies.

5. Confusing a Class Curve with Your Own

A curve applies to the whole class, not just to you.

The math is exact for each method, but real curving policies can be more nuanced.

Common methods add a flat number of points, set the highest score to 100 and shift everyone up, or apply a square-root curve that lifts low scores most. The method is up to the instructor.

It finds the gap between the top raw score and 100, then adds that gap to every score. If the class high is 88, everyone gains 12 points.

It replaces each score with ten times its square root, so a 64 becomes 80. It helps lower scores more than high ones, which is why instructors use it after a hard test.

Usually a little, but not always by much. Most curves add modest points and rarely turn a low raw score into a top grade.

A true bell curve that assigns fixed grade quotas can, in theory, but the common curves here only add points, so they do not lower a score.

Enter your raw score and the method to see the exact gain. The highest-score curve helps everyone equally, while the square-root curve helps lower scores most.

Only your instructor knows. Many classes are not curved at all, so do not assume one unless it is stated.

The tool maps your curved score to a letter using standard cut-offs, though your school exact ranges may differ slightly.

No. The calculation runs entirely in your browser and nothing you enter is stored or sent anywhere, unless you choose Save, which keeps the result only in this browser.

• Grading on a curve (Wikipedia).
• Academic grading in the United States (Wikipedia).
• Square root and functions (Maths Is Fun).