acalculator

How does the grade curve work?

Type your score, the points possible, and the class’s highest score. The grade curve calculator shows your curved grade with a flat, scaled or linear curve.

Your numbers

Curve
Curved grade
83.00%

Your curved grade is 83.00%.

Raw grade
75.00%
Curved score (points)
83
Points added
8
Rule
curved % = raw % + (100.00 − 92.00) = raw % + 8.00

Curved grade: 83.00%. Your curved grade is 83.00%.

How to calculate

Curves a test score three ways: a flat curve that adds points, a scale that multiplies, or a linear curve that maps the class’s lowest and highest scores onto a new range.

Example with the default inputs (Curve Flat (add points), Your score (points) 75, Points possible 100, Highest score in the class 92, Curve the top score to 100%): Your curved grade is 83.00%.

Method: Raw % = score ÷ points possible × 100, and top % the same for the highest score. Flat: curved % = raw % + (target − top %). Scale: curved % = raw % × target ÷ top %. Linear: curved % = new low + (target − new low) ÷ (top % − low %) × (raw % − low %).

  • Every score is on the same test, out of the same points possible; your score is at most the highest score.
  • A curve can give more than 100% if you set the target above 100%; nothing is capped.
  • Values are taken exactly as typed; percents are shown to 2 decimal places, halves away from zero.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. Curve Flat (add points), Your score (points) 75, Points possible 100, Highest score in the class 92, Curve the top score to 100% gives Curved grade 83.00%, Raw grade 75.00%, Curved score (points) 83, Points added 8.Source: CompSci.rocks, Should you grade on a curve? (flat curve: subtract the highest score from a perfect score and add the difference to everyone; linear distribution: Score = Y₀ + [(Y₁ − Y₀)/(X₁ − X₀)] × (Z − X₀), 72% with scores 55 to 96 curved to 60 to 100 is about 77%), https://compsci.rocks/blog/curve-grades/ (retrieved 2026-10-05)
  2. Curve Linear (low to high), Your score (points) 72, Points possible 100, Highest score in the class 96, Lowest score in the class 55, Curve the top score to 100%, Curve the lowest score to 60% gives Curved grade 76.59%, Curved score (points) 76.585366, Points added 4.585366.Source: CompSci.rocks, Should you grade on a curve? (flat curve: subtract the highest score from a perfect score and add the difference to everyone; linear distribution: Score = Y₀ + [(Y₁ − Y₀)/(X₁ − X₀)] × (Z − X₀), 72% with scores 55 to 96 curved to 60 to 100 is about 77%), https://compsci.rocks/blog/curve-grades/ (retrieved 2026-10-05)
  3. Curve Scale (multiply), Your score (points) 34, Points possible 40, Highest score in the class 38, Curve the top score to 100% gives Curved grade 89.47%, Raw grade 85.00%, Curved score (points) 35.789474.Source: CompSci.rocks, Should you grade on a curve? (flat curve: subtract the highest score from a perfect score and add the difference to everyone; linear distribution: Score = Y₀ + [(Y₁ − Y₀)/(X₁ − X₀)] × (Z − X₀), 72% with scores 55 to 96 curved to 60 to 100 is about 77%), https://compsci.rocks/blog/curve-grades/ (retrieved 2026-10-05)
  4. Curve Linear (low to high), Your score (points) 156, Points possible 200, Highest score in the class 194, Lowest score in the class 0, Curve the top score to 100%, Curve the lowest score to 23.5% gives Curved score (points) 170.030928, Curved grade 85.02%.Source: Texas A&M, Math 467 grades page (a linear curve: scores × 0.79 + 47 raise the top score 194 to 200 and the median 156 to 170), https://people.tamu.edu/~fulling/m467/s09/grades.html (retrieved 2026-10-05); CompSci.rocks, Should you grade on a curve? (flat curve: subtract the highest score from a perfect score and add the difference to everyone; linear distribution: Score = Y₀ + [(Y₁ − Y₀)/(X₁ − X₀)] × (Z − X₀), 72% with scores 55 to 96 curved to 60 to 100 is about 77%), https://compsci.rocks/blog/curve-grades/ (retrieved 2026-10-05)

How it works

All three rules work on percents. With S your score, P the points possible and H the highest score in the class (all in points):

  • Raw % = S ÷ P × 100, and top % = H ÷ P × 100.
  • Target: the percent the highest score should become (100% by default, from 0% to 1,000%).

The three curves:

  1. Flat (add points). curved % = raw % + (target − top %). Everyone gets the same number of percentage points.
  2. Scale (multiply). curved % = raw % × target ÷ top %. This is the linear rule below with 0 kept at 0. The highest score must be above 0.
  3. Linear (low to high). With L the lowest score in the class, low % = L ÷ P × 100, and a new low (60% by default): curved % = new low + (target − new low) ÷ (top % − low %) × (raw % − low %). The lowest score must be below the highest, and your score at least the lowest.

Then curved points = curved % × P ÷ 100 and points added = curved points − S.

Rules. Your score cannot be above the highest score (no answer). Scores and points are from 0 to 1,000,000; the points possible are at least 0.0001. Nothing is capped at 100%.

Exact arithmetic. Every value is read exactly as typed, so each result is an exact fraction until it is rounded for display.

Output format. The curved and raw grades are text with exactly 2 decimal places and a % sign, rounded half away from zero. Curved points and points added show to 2 decimal places. The rule line shows the formula with the values to 2 decimal places.

Worked examples by hand

Flat. Score 75 of 100, top 92. Add 100 − 92 = 8: curved 83.00%, 83 points, 8 points added.

Linear (the CompSci.rocks example). Scores from 55 to 96, curved to 60 to 100; your 72: 60 + (100 − 60) ÷ (96 − 55) × (72 − 55) = 60 + 40 ÷ 41 × 17 = 76.585…, so 76.59%, 4.59 points added.

Scale. 34 of 40 (85%), top 38 of 40 (95%): 85 × 100 ÷ 95 = 89.473…, so 89.47%, which is 35.79 points.

Linear, two points (close to the Texas A&M curve). Out of 200, the lowest 0 goes to 23.5% (47 points) and the top 194 (97%) to 100%. A 156 (78%): 23.5 + 76.5 ÷ 97 × 78 = 85.015…%, so 85.02%, or 170.03 points. Texas A&M's rounded rule, × 0.79 + 47, gives 170.2.

Other questions people ask

How does a flat curve work?

Find how far the top score is from 100% and add that to everyone. If the top score is 92%, everyone gets 8 points: a 75% becomes 83%.

What is the difference between a flat curve and a scale?

A flat curve adds the same points to everyone. A scale multiplies, so the top score lands on 100% and every score keeps its ratio to it: with a top of 95%, 85% becomes 85 × 100 ÷ 95 = 89.47%. A scale adds fewer points to low scores.

How does a linear curve work?

It stretches the range of scores. The lowest score is moved to a new low (say 60%) and the highest to a new high (say 100%), and every score in between keeps its place. With scores from 55% to 96%, a 72% becomes 60 + 40 ÷ 41 × 17 = 76.59%.

Does a curve ever lower a score?

Not when the target is at least the top score’s percent, which is the usual case. A linear curve can lower some scores only if the new low is below the old lowest percent or the target is below the old top percent.

Can a curved grade be over 100%?

Only if you set the target for the top score above 100%. With a target of 100%, the top score becomes exactly 100% and no one goes over.

What about the square root curve?

It is a fourth rule: 10 × √(raw %), so 64% becomes 80%. The square root curve calculator does it.