Statistics calculator

Mean, median, standard deviation and other basic stats.

Sample standard deviation (n-1)

Count	-
Sum	-
Mean	-
Median	-
Min / Max	-
Range	-
Variance	-
Standard deviation	-

Calculated automatically as you enter numbers.

You have a column of numbers — test scores, response times, monthly totals — and you want the basic descriptive figures without opening a spreadsheet. Paste them in and the results appear as you type.

Separators are flexible: spaces, commas or line breaks all work, so you can copy straight out of a spreadsheet column or a log file. One checkbox switches between the sample and population standard deviation.

How it works

Entering data

Type or paste numbers into the box separated by spaces, commas or line breaks — mixing them is fine. Results recalculate automatically as you type; there is no button to press. Decimals and negative numbers are accepted.

What each figure means

Statistic	How it is computed
Count	How many values were parsed
Sum	All values added together
Mean	Sum divided by count
Median	The middle value once sorted (the average of the two middle values when the count is even)
Min / Max	Smallest and largest values
Range	Max minus min
Variance	Average squared distance from the mean
Standard deviation	The square root of the variance

Sample or population

The checkbox labelled Sample standard deviation (n-1) controls the divisor. With it on, the sum of squared deviations is divided by n - 1; with it off, by n.

Use the sample setting when your numbers are a subset drawn from a larger group you want to draw conclusions about — the n - 1 divisor corrects a bias that would otherwise make the spread look smaller than it is. Use the population setting only when your data covers the entire group. The difference shrinks as the dataset grows and matters most for small ones.

Mean and median are worth reading together: when they diverge sharply, the data is skewed or contains outliers, and the mean alone will mislead.

Terms explained

Mean: The arithmetic average - the sum divided by the count. Sensitive to outliers.
Median: The middle value when the data is sorted. Less affected by extreme values than the mean.
Range: The distance between the smallest and largest value. A quick but crude measure of spread.
Variance: The average of the squared differences from the mean. Its units are the square of the original units.
Standard deviation: The square root of the variance, expressed in the same units as the data - the usual measure of spread.
Sample vs population (n-1): Whether the data is a subset of a larger group (divide by n-1) or the whole group (divide by n).

Frequently asked questions

Should I use the sample or the population standard deviation?

Use the sample setting (n-1) when your numbers are a subset drawn from a larger group and you want to say something about that group - which covers most real analyses. Use the population setting only when the data covers every member of the group you care about, such as the final scores of an entire class you are describing and nothing more.

Why do the mean and the median differ so much in my data?

A large gap means the distribution is skewed or contains outliers. A few very large values pull the mean upward while leaving the median roughly where it was. When they diverge, the median usually describes a typical value better, and it is worth looking at the min and max to see what is driving the skew.

What separators can I use between numbers?

Spaces, commas and line breaks all work, and you can mix them freely in the same input. That means you can paste a spreadsheet column, a comma-separated list or a block of log output directly without cleaning it up first.

Does the calculator accept negative numbers and decimals?

Yes. Both are parsed normally and included in every statistic. Just make sure a stray character has not merged two values together - check that the count matches how many numbers you expected.

Is my data sent to a server?

The calculation runs in your browser as you type, which is why results update without a submit step. Even so, avoid pasting sensitive personal or confidential data into any web tool as a general habit.