Bell Curve Grade Calculator
Assign letter grades on a normal curve.
Enter your values
Enter the raw score you are working with.
Enter the class mean you are working with.
Enter the class sd you are working with.
Enter the target mean you are working with.
Enter the target sd you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Curved score
- 80.5%
- Letter grade
- B-
- Z-score
- 0.55
- Points gained
- 16.5
Quick answer
Curving shifts scores so the class mean lands on a chosen target while preserving the spread.
Curved = target + (score − mean) × (targetSD ÷ SD)
At a glance
| What it does | Assign letter grades on a normal curve. |
|---|---|
| Category | Education |
| Inputs needed | Raw score, Class mean, Class SD, Target mean, Target SD |
| Main output | Curved score |
| Formula | Curved = target + (score − mean) × (targetSD ÷ SD) |
| Cost | Free — no sign-up, no download |
How to use the Bell Curve Grade Calculator
- 1Enter the raw score and the class statistics.
- 2Choose the target mean and spread.
- 3Read the curved score and letter grade.
Inputs explained
- Raw score
- Enter the raw score you are working with.
- Class mean
- Enter the class mean you are working with.
- Class SD
- Enter the class sd you are working with.
- Target mean
- Enter the target mean you are working with.
- Target SD
- Enter the target sd you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Raw score64
- Class mean58
- Class SD11
- Target mean75
- Target SD10
Results
- Curved score80.5%
- Letter gradeB-
- Z-score0.55
- Points gained16.5
Frequently asked questions
Is curving fair?
It normalises for a hard paper but also caps how many students can earn top grades.
What target mean is common?
Many instructors curve to a 75 mean.
What do I need to enter into the Bell Curve Grade Calculator?
Just 5 values: raw score, class mean, class sd, target mean, target sd. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Bell Curve Grade Calculator work out the answer?
Curving shifts scores so the class mean lands on a chosen target while preserving the spread. It applies the formula Curved = target + (score − mean) × (targetSD ÷ SD) and shows the working so you can check each step by hand.
Is the Bell Curve Grade Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.