About the Class Grade Statistics Calculator
This class grade statistics calculator summarizes a whole set of test or assignment scores at once. Paste the scores — separated by commas, spaces or new lines, straight from a spreadsheet column — and set the points possible. You get the class average, median, highest and lowest score, standard deviation, quartiles, the pass rate and a histogram of A, B, C, D and F grades.
Teachers use it after marking to see whether a test was too hard or too easy, to report results to a department, or to decide whether a curve is justified. A large gap between the mean and the median points to a few very high or very low scores pulling the average, and a wide standard deviation means the class split into very different levels of mastery.
Scores are converted to percentages of the points possible before grading, using the common 90/80/70/60 letter bands. The standard deviation shown first treats the list as the whole class (population); the sample version is also given if you are treating one section as a sample of a larger group.
With the default inputs, the class average is 79.6. Change any value above to recalculate instantly.
How to use the class grade statistics calculator
- 1Copy the score column from your gradebook or spreadsheet.
- 2Paste it into the scores box — commas, spaces or new lines all work.
- 3Enter the points possible for the test.
- 4Set the passing percentage your school uses.
- 5Review the average, spread and A–F distribution chart.
Formula and method
The class average is the sum of all scores divided by the number of scores. The median is the middle score after sorting (the average of the two middle scores when the count is even). The population standard deviation σ measures the typical distance of scores from the mean using all n students; the sample version s divides by n − 1 instead and is slightly larger.
Quartiles use linear interpolation between sorted scores (the same method as Excel’s PERCENTILE.INC). For the grade distribution, each score is converted to a percentage of the points possible and placed in a band: A 90%+, B 80–89%, C 70–79%, D 60–69%, F below 60%. The pass rate is the share of scores at or above the passing percentage.
- x
- An individual student score
- n
- Number of scores
- σ
- Population standard deviation
- s
- Sample standard deviation
Worked examples
Class of 20 on a 100-point test
The 20 scores add to 1,592, so the average is 79.6 and the median of the two middle scores (81 and 83) is 82. Scores sit about 12.2 points from the mean on average, and 18 of 20 students reached 60%, a 90% pass rate.
Quiz out of 25 points
Eight scores total 154, an average of 19.25 out of 25 or 77%. As percentages the scores are 88, 72, 100, 60, 80, 48, 92 and 76, so only the 12 (48%) is below the 60% pass mark.
Small group with a 70% pass mark
The five scores average 375 ÷ 5 = 75 with a median of 72. With a stricter 70% pass mark, three of five students pass (60%).
Frequently asked questions
How do I calculate a class average?+
Add every student’s score and divide by the number of students. For example, scores of 80, 90 and 70 total 240, and 240 ÷ 3 gives a class average of 80.
Should I use the mean or the median for test scores?+
Report both. The mean uses every score but is pulled by outliers such as a zero for a missed test; the median is the middle score and better represents a typical student when results are skewed.
What does the standard deviation of test scores tell me?+
It measures how spread out the scores are. A small standard deviation (say 5 points) means most students scored close to the average; a large one (15+ points) means results ranged widely.
Population or sample standard deviation — which should teachers use?+
If the scores are the entire class you are describing, use the population standard deviation. Use the sample version when the class is a sample used to estimate a larger group, such as all students taking the course.
What is a normal grade distribution for a test?+
There is no single standard, but many teachers aim for an average in the 70s or low 80s with relatively few F grades. A distribution bunched near 100% may mean the test was too easy to separate levels of mastery.