Curve an entire class's grades in seconds. Choose from 5 professional methods — linear rescaling, square root, flat bonus, target mean, or proportional scaling. See before vs after for every student instantly.
Grade Curve Calculator
Grade Curve Calculator
Linear Rescaling: The highest score in the class becomes 100%. All other scores are scaled up proportionally. Best when one student aced it and the rest were clustered below.
Bonus Points to AddAdded to every student's raw score
Target Class MeanDesired average score after curving
Desired Top ScoreWhat the highest raw score should become
Max Possible ScoreFull marks on this test
Cap Curved Scores atPrevent scores exceeding this
🎓 Student Scores 0 students
Student NameRaw ScoreCurved ScoreLetter Grade
📊 Curve Results
Before vs After — Score Comparison
Before CurveAfter Curve
Full Grade Report
#
Student
Raw Score
Curved Score
Change
Letter Grade
How to Use
How to Use the Grade Curve Calculator
Whether you are a teacher adjusting scores after a difficult exam or a student trying to understand how a curve will affect your grade, this calculator handles it in seconds — for unlimited students, with full before-and-after comparison.
1
Choose a Curve Method
Select from 5 methods: Linear Rescaling scales everyone up so the top score becomes 100. Square Root applies the classic √score × 10 formula. Flat Bonus adds fixed points to every student. Target Mean shifts the whole class to a desired average. Proportional Scaling adjusts by a custom ratio.
2
Set Your Parameters
Enter the maximum possible score for the test. Depending on your chosen method, also enter bonus points, target mean, or desired top score. Set a cap (usually 100) to prevent any curved score from exceeding the maximum.
3
Enter Student Scores
Add each student's name and raw score. There is no limit — add as many students as your class has. Scores update live as you type. You can add or remove students at any time.
4
Click Apply Curve & Export
Hit Apply Curve to see every student's curved score, letter grade, and the exact change in points. View the before-vs-after chart, then export the full results as a CSV file for your gradebook.
About This Tool
What Is a Grade Curve?
A grade curve is an adjustment teachers apply to a set of exam scores when the raw results do not accurately reflect student understanding — usually because the test was harder than intended. Instead of leaving a class with a low average, the teacher applies a mathematical formula to raise all scores proportionally or by a fixed amount.
Grade curving is standard practice in universities and high schools worldwide. The method chosen depends on the situation: a flat bonus is quickest; linear rescaling is fairest when one student aced it; square root curving benefits lower scorers more than higher scorers; and target mean curving gives the teacher full control over where the class average lands.
Important: Not all curves are equal. A flat +10 bonus helps a 50% student more in letter-grade terms than it helps a 90% student. Square root curving benefits struggling students the most. Always choose your method based on what outcome is fairest for your specific class distribution.
The 5 Grade Curve Formulas Explained
Method
Formula
Example (raw 70, max 100)
Best For
Linear Rescaling
(Score ÷ Highest Score) × 100
If top score = 85: (70÷85)×100 = 82.4%
When top score is below 100
Square Root
√Score × 10
√70 × 10 = 83.7%
Helping lower scorers more
Flat Bonus
Score + Bonus Points
70 + 10 = 80%
Quick uniform adjustment
Target Mean
Score + (Target − Current Mean)
If mean=65, target=75: 70+10 = 80%
Controlling class average
Proportional Scaling
(Score ÷ Max) × Desired Top
(70÷100)×100 = 70%
Custom ratio adjustments
"The square root curve is mathematically elegant: it compresses the top end and expands the bottom, so a student who scored 64% jumps to 80% while a student who scored 81% only moves to 90%. It rewards effort without punishing excellence."
Helpful Guide
Related Article You May Find Useful
A step-by-step guide to understanding and applying grade curves — with worked examples for every method.
Curving grades means adjusting raw exam scores upward using a mathematical formula, so the final grades better reflect student understanding. It is used when a test was unexpectedly difficult and the raw scores are lower than intended. Curving does not mean everyone passes — it shifts the whole distribution up.
Linear rescaling — where the highest score becomes 100% and all others are scaled up — is the most widely used method in universities. The square root curve is the second most common, especially in high school, because it benefits struggling students without dramatically inflating top scores.
The square root curve formula is: Curved Score = √(Raw Score) × 10. For example, a raw score of 64 becomes √64 × 10 = 80. A raw score of 81 becomes √81 × 10 = 90. This method compresses the high end and stretches the low end — so students who struggled gain more than students who already did well.
A flat bonus adds the same number of points to every student — so a student with 70 and a student with 90 both get +10. Linear rescaling is proportional — the student who scored highest gets the biggest boost in absolute terms, but everyone ends up on the same relative scale with the top score becoming 100%. Flat bonuses are simpler; linear rescaling is more mathematically precise.
With flat bonus and target mean methods, it is possible for high scorers to exceed 100% after the curve. This calculator includes a "Cap Curved Scores at" field (default 100) to prevent this. You can also set it higher — for example, cap at 105 if your school allows extra credit scores above 100.
Yes — there is no student limit. Add as many rows as your class has. The calculator processes all students instantly and shows a full report with before-vs-after comparison, class statistics (mean, highest, lowest, standard deviation), and a visual chart. You can also export everything to CSV for your gradebook.
The target mean method calculates the current class average, then adds a fixed bonus to every student so the new average equals your target. For example, if the class averaged 63% and you want a 75% average, every student gets +12 points. It is the most controlled method — you decide exactly where the class average lands.
Yes — completely free. No sign-up, no account, no subscription required. All calculators on Easy Quick Grade are 100% free and work on any device including smartphones and tablets.
