What is my square root curve grade?
Type your score and the points possible to curve it with the square root rule. The square root curve calculator gives the curved percent, 10 × √(raw percent), and how many points the curve added. Or type a curved grade to find the raw score that earns it.
- Curved grade
- 80%
Your curved grade is 80%.
- Raw grade
- 64%
- Points added by the curve
- 16
Curved grade: 80%. Your curved grade is 80%.
Curved grade by your score (points)
How to calculate
Curves a test score with the square root rule: the curved percent is 10 × √(raw percent), so 64% becomes 80%. Or finds the raw score that gives a curved percent.
Example with the default inputs (Your score (points) 64, Points possible 100): Your curved grade is 80%.
Formula: curved % = 100 × √(score ÷ total) = 10 × √(raw %). To find the score for a curved grade: score = total × (curved ÷ 100)².
- The curve is applied to the percent score: 10 × √(raw %). A raw 100% stays 100% and 0% stays 0%.
- A score above the points possible (extra credit) gives a curved grade above 100%.
- Values run in double precision; the curved grade is shown to 2 decimal places.
Worked examples
Each example is checked against the calculator on every build.
- Your score (points) 64, Points possible 100 gives Curved grade 80%, Raw grade 64%, Points added by the curve 16.Source: CompSci.rocks, Should you grade on a curve? (take the square root of the grade and multiply by 10; 25 becomes 50), https://compsci.rocks/blog/curve-grades/ (retrieved 2026-10-02)
- Your score (points) 36, Points possible 50 gives Curved grade 84.852814%, Raw grade 72%.Source: CompSci.rocks, Should you grade on a curve? (take the square root of the grade and multiply by 10; 25 becomes 50), https://compsci.rocks/blog/curve-grades/ (retrieved 2026-10-02)
- Curved grade 70%, Points possible 100 gives Your score (points) 49.Source: CompSci.rocks, Should you grade on a curve? (take the square root of the grade and multiply by 10; 25 becomes 50), https://compsci.rocks/blog/curve-grades/ (retrieved 2026-10-02)
How it works
The square root curve is a rule a teacher can choose. Written out:
- curved % = 10 × √(raw %), where raw % = score ÷ points possible × 100
- the same rule in points: curved % = 100 × √(score ÷ points possible)
- the score that gives a curved grade: score = points possible × (curved % ÷ 100)²
- points possible from a score and a curved grade: points possible = score ÷ (curved % ÷ 100)²
- points added by the curve = curved % − raw %, in percentage points
Type any two of score, points possible and curved grade. The maths runs in double precision.
Rules
- The score is from 0 to 1,000,000 points; points possible are more than 0 and at most 1,000,000; the curved grade is from 0% to 1,000%. A solved value outside these bounds, or points possible from a curved grade of 0%, has no answer.
- A score above the points possible (extra credit) is allowed and gives a curved grade above 100%.
Output format. Curved and raw grades as percents to 2 decimal places; points added to 2 decimal places.
Worked examples by hand
64 out of 100. raw 64%; curved 10 × √64 = 80%; the curve adds 16 points.
36 out of 50. raw 36 ÷ 50 = 72%; curved 100 × √0.72 = 84.85%.
The score that curves to 70%. 100 × (70 ÷ 100)² = 49 points out of 100.
Other questions people ask
How does a square root curve work?
Take the raw percent, find its square root, and multiply by 10. A raw 64% becomes 10 × √64 = 80%. The same rule written with points is 100 × √(score ÷ points possible).
What does a 50% become on a square root curve?
10 × √50 = 70.71%. Lower scores gain the most: 25% becomes 50%, 50% becomes 70.71%, 81% becomes 90%, and 100% stays 100%.
What raw score do I need for a 70% after the curve?
Reverse the rule: raw % = (curved % ÷ 10)². For 70%, (70 ÷ 10)² = 49%, so 49 points out of 100. Type 70 as the curved grade and leave your score empty.
Can the square root curve lower a grade?
No, not for scores from 0% to 100%. The square root of a number between 0 and 1 is at least as large as the number, so every curved grade is at least the raw grade. Only 0% and 100% stay the same.
What if my score is not out of 100?
Type the points possible. The page divides your score by it first: 36 out of 50 is 72%, and 10 × √72 = 84.85%.
Is the square root curve standard?
No. It is one way a teacher may choose to curve grades, and some use other curves (adding points, scaling to the top score, or a bell curve). Check with your teacher how your class is curved.