Quick answer
A grade curve shifts scores so the top student reaches a target. The flat curve adds the same number of points to everyone (91 → 100 adds 9), while the scale curve multiplies every score by target ÷ highest. For 62, 75, 88 and 91 the flat curve gives 71, 84, 97 and 100.
Enter the class's raw scores, the score the top student should get and the kind of curve. You get the curved scores and the adjustment applied.
Related tools: Grade Calculator: Percentage grade from points earned and points possible. Final Grade Calculator: The score needed on a final exam to reach a target course grade. Weighted Grade Calculator: Course grade from scores and their weights.
How to use the Grade Curve Calculator
- Type scores, for example 62, 75, 88.
- Enter score the top student should get (above 0). It starts at 100.
- Choose curve: Add points so the top score reaches the target and Scale all scores proportionally.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Scores | Text, such as 62, 75, 88 | — |
| Score the top student should get | A number | > 0, starts at 100 |
| Curve | Choose one: Add points so the top score reaches the target; Scale all scores proportionally | Starts at Add points so the top score reaches the target |
Formula and method
Formula
flat: new = score + (target − highest); scale: new = score × target ÷ highest
IEEE-754 double precision; shown to the decimals indicated.
Flat curves are capped at the target.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Scores = 62, 75, 88, 91; Score the top student should get = 100; Curve = Add points so the top score reaches the target.
| Result | Value |
|---|---|
| Curved scores | 71, 84, 97, 100 |
| Curve applied | 9 points |
Example 2
Inputs: Scores = 40, 55, 80; Score the top student should get = 100; Curve = Scale all scores proportionally.
| Result | Value |
|---|---|
| Curved scores | 50, 68.75, 100 |
| Curve applied | × 1.25 |
Example 3
Inputs: Scores = 70, 85; Score the top student should get = 95; Curve = Add points so the top score reaches the target.
| Result | Value |
|---|---|
| Curved scores | 80, 95 |
| Curve applied | 10 points |
The first line is the headline result (curved scores). Below it the grade Curve Calculator lists curve applied, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Flat versus scaled
Flat: new = score + (target − highest). Everyone gains the same number of points, so the gaps between students stay identical. Scaled: new = score × target ÷ highest. Every score is multiplied by the same factor, so high scorers gain more points than low scorers.
With a top score of 91 and a target of 100, the flat curve adds 9 to each score. The scale curve multiplies by 100 ÷ 91 ≈ 1.099, so 62 becomes 68.1 instead of 71.
This is not a bell curve
The page uses a 'raise the top score' method, the one most instructors mean by 'curving'. It does not force a normal distribution or assign grades by rank; competitors also offer a bell-curve option, which this tool does not.
How the result changes with score the top student should get
Holding every other input at the first worked example, this table changes only score the top student should get. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Score the top student should get | Curved scores | Curve applied |
|---|---|---|
| 50 | 21, 34, 47, 50 | -41 points |
| 100 | 71, 84, 97, 100 | 9 points |
| 200 | 171, 184, 197, 200 | 109 points |
| 400 | 371, 384, 397, 400 | 309 points |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Scores: left empty shows "Enter scores." beside that field and no result.
- Score the top student should get: entering "0" shows "Score the top student should get must be greater than 0." beside that field and no result.
Choosing between the Grade Curve Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Grade Calculator](/education/grade-calculator/) | points earned and points possible | Grade |
| [Final Grade Calculator](/education/final-grade-calculator/) | current grade, grade you want and final exam weight | Score needed on the final |
| [Weighted Grade Calculator](/education/weighted-grade-calculator/) | scores and weights | Weighted grade |
| [Class Rank Percentile Calculator](/education/class-rank-percentile-calculator/) | your rank and class size | Percentile |
| [Weighted GPA Calculator](/education/weighted-gpa-calculator/) | grade points per course, credits per course and extra points per course | Weighted GPA |
Assumptions and limitations
- Your instructor's policy decides
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for scores and score the top student should get to confirm this.
Frequently asked questions
Which curve is fairer?
Neither is objectively fairer. The flat curve helps low scorers more in relative terms; the scale curve keeps proportions.
Can a curve lower grades?
If the target is below the highest score, the flat option would subtract points. Enter a target at or above the top score.
Should I curve to 100?
Many instructors curve so the top score becomes 100, but others only raise the median. Follow the course policy.
What does the Grade Curve Calculator calculate?
Apply a flat or proportional curve to a set of scores. It returns Curved scores and Curve applied.
What formula does the Grade Curve Calculator use?
flat: new = score + (target − highest); scale: new = score × target ÷ highest. Flat curves are capped at the target.
What do I need to enter in the grade Curve Calculator?
You enter Scores, Score the top student should get and Curve.
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Your instructor's policy decides.
What does the “Curve” option change?
It sets how the grade Curve is worked out. The choices are Add points so the top score reaches the target and Scale all scores proportionally.
What is an example of a grade Curve result?
With scores 62, 75, 88, 91, score the top student should get 100 and curve Add points so the top score reaches the target, the curved scores is 71, 84, 97, 100.
Related calculators
- Grade Calculator — Percentage grade from points earned and points possible.
- Final Grade Calculator — The score needed on a final exam to reach a target course grade.
- Weighted Grade Calculator — Course grade from scores and their weights.
- Class Rank Percentile Calculator — Percentile from class rank and class size.
- Weighted GPA Calculator — GPA with extra points for honors or advanced courses.
- Letter Grade to GPA Calculator — Grade points for a letter grade on the 4.0 scale.
Sources
- OpenStax, Prealgebra 2e (Rice University): fractions, decimals, percents, ratios and rounding
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.