How to use the Relative Grading Z-Score Calculator
- 1. Enter your marksType your marks in the subject.
- 2. Add class dataEnter the class mean and SD, or paste every student's marks.
- 3. Set the bandsKeep the example bands or type your institute's cut-offs, then see your grade.
What a z-score tells you
In relative grading, your grade depends on how you did compared to the class, not on a fixed percentage. The z-score measures this: z = (your marks − class mean) ÷ standard deviation. A z of 0 is exactly average, +1 is one SD above, and −1 is one SD below.
Worked example with the defaults: marks 68, mean 55, SD 12. z = (68 − 55) ÷ 12 = 1.08. With the example bands, z of 1 or more is an A, so the grade is A. On a normal curve, a z of 1.08 is about the 86th percentile.
Grade bands differ by institute
The bands in the tool are only an example. Some institutes set cut-offs at mean ± a number of SDs, some give fixed shares of the class each grade, and some mix in absolute minimums. Copy your institute's published method if it has one. The tool also shows the marks each band needs: mean + band z × SD.
If you paste all marks, the tool uses the population SD of the list and also shows your actual percentile rank in the class. For a general z-score or probability, use the z-score calculator. For percentiles of any list, use the percentile calculator.
Frequently asked questions
Are these grade bands official?
No. They are an example. Use the cut-offs your institute publishes or your professor announces.
Why is the percentile marked as an estimate?
It assumes the marks follow a bell curve. Real class marks are often skewed, so paste the marks to see your actual rank.
Which SD should I use?
Use the SD your professor shares. If you paste the marks, the tool uses the population SD of the whole class.
Is this tool free?
Yes. You enter your name and WhatsApp number once when you see your result, and other Uncodemy tools then open without the form.