BYTETOOLS

Grade Distribution Calculator

Turn a list of class scores into a letter-grade histogram with mean, median, mode, standard deviation, pass rate and the percentile rank of any score.

Paste a set of class scores above to see the grade distribution, averages and spread.

The standard deviation shown is the sample version (dividing by n − 1), which is the usual choice when a class is treated as a sample of a wider cohort. Letter cutoffs and the pass mark vary by country, school and even by course, which is why both are editable here. Every calculation runs in your browser and no scores are uploaded.

What is the Grade Distribution Calculator?

A grade distribution calculator groups class scores into letter-grade bands against a cutoff table and reports the shape of the results: mean, median, mode, standard deviation, range, pass rate and each score's percentile rank.

  • SVG bar chart of the letter-grade distribution with counts and percentages
  • Mean, median, mode, sample standard deviation, range and pass rate together
  • Editable cutoff table instead of one hardcoded national grading scale
  • Percentile rank lookup counting ties as half, the standard convention
  • Sample class button so you can see the output before pasting real data
  • Copyable text summary of every statistic and band count

How to use the Grade Distribution Calculator

  1. 1

    Paste the class scores into the box, separated by commas, spaces or new lines.

  2. 2

    Edit the letter-grade cutoffs so they match the scale you actually use.

  3. 3

    Set the pass mark used for the pass-rate figure.

  4. 4

    Read the histogram, the band table and the summary statistics.

  5. 5

    Type any single score into the lookup box to see its percentile rank.

About the Grade Distribution Calculator

The ByteTools Grade Distribution Calculator takes a pasted set of class scores and shows you what the results actually look like. You get a bar chart of how many students landed in each letter band, alongside the mean, median, mode, standard deviation, highest and lowest marks, the range and the pass rate.

The letter cutoffs are an editable field rather than a fixed assumption, because grading bands differ by country, institution and course. Change 90/80/70/60 to your own scale, or to a pass and fail split, and the chart and table update immediately. The pass mark used for the pass-rate figure is separate and adjustable too.

A lookup box gives the percentile rank of any single score, counting everyone below plus half of those who tied. All of this happens inside your browser: the scores you paste are never uploaded, which is what makes the tool usable with a real class list.

Frequently asked questions

How do you calculate percentile rank for a test score?

Count the scores below the one you are ranking, add half the scores equal to it, divide by the total number of students and multiply by 100. Counting ties as half is the standard convention and is what this tool uses.

Should I use sample or population standard deviation for a class?

This tool reports the sample version, dividing by n minus 1, which is the usual choice when a class is treated as a sample of a wider cohort. For a fixed group you never intend to generalise from, the population version is slightly smaller.

What does the standard deviation of a class tell me?

It measures how spread out the marks are. A small standard deviation means most students scored close to the average, while a large one signals a wide gap between the strongest and weakest performances that an average alone hides.

Why can a class have no mode?

The mode is the most frequently occurring score, so if every student got a different mark nothing repeats and there is no mode. This calculator says so rather than inventing one, and it lists all tied values when several scores share the top frequency.

Are grade cutoffs the same everywhere?

No. A 90/80/70/60 split is common in the United States, but many institutions use 93 for an A, and UK and Indian scales look nothing like either. That is exactly why the cutoff table here is an editable field.

Is my class data private?

Yes. The scores are parsed and analysed by JavaScript in your own browser tab. Nothing is uploaded, stored or logged, and the page continues to work if you disconnect from the network.

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