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Grade Curve Calculator: Curve Test Scores

This free tool curves a set of test scores. Add points, add a percentage, scale the highest score up to 100 or use the square root curve, then read the new score of each student and the class average.

By Debmedia Technologies LLP · Kolkata, India · Updated

What Is It and When Do You Need It?

A hard test can pull down a whole class. Teachers curve scores to bring them back in line, and students use a calculator to see what a curve might do.

Paste the scores, choose a method and type the number it needs.

How to Use This Tool

  1. Enter or paste your input in the box or boxes above.
  2. Choose the options, if there are any.
  3. Press the button to run the tool.
  4. Read the result and use the copy button where one is shown.

How the Calculation Works

Add points adds the same amount to every score. Add percent adds the percent of the points possible. Scale makes the top score equal to the maximum and multiplies all others by the same ratio. Square root takes 10 times the square root of each score on a 100 point scale, and the tool scales it to other maximums. Average shift adds the difference between the target and the current average. All results are capped at the maximum.

Worked Example

For scores 60, 70 and 80 out of 100, adding 5 points gives 65, 75 and 85. Scaling the top score to 100 gives 75, 87.5 and 100.

Common Uses

  • Teachers curving a test.
  • Students checking what a curve could do.
  • Comparing methods.
  • Class reports.

Tips and Common Mistakes

  • Try several methods and compare the averages.
  • Do not curve below zero.
  • Check school policy before you use a curve.
  • Check the first result against a case you already know, so you can trust the tool for the rest.
  • Nothing you type leaves your device. The work is done by your browser, so it also works with a slow connection once the page has loaded.

Next, you may need the grade calculator, GPA calculator, percentage calculator, average calculator.

Everything runs in your browser. Nothing you type is uploaded, stored or sent to any outside service.

Frequently Asked Questions

Changing all scores in a class by the same rule so the results are fairer when a test was harder than planned.
There is no single answer. Adding points helps everyone equally. Scaling to the top score helps the lower scores a little more, and the square root curve lifts low scores most.
No. The tool caps every new score at the points possible.
No. It is a calculation. Follow your teacher or school policy.

Disclaimer: results are calculated in your browser from the numbers you enter. Check important results before you rely on them for money, health, safety or legal decisions.