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Statistics Calculator
Paste a list of numbers to get the mean, median, mode, range, quartiles, standard deviation and variance (sample and population), standard error, and possible outliers.
Statistics Calculator: The calculator works out the standard descriptive statistics with numerically careful methods: variance uses Welford's algorithm, which stays accurate for large numbers close together. Quartiles follow either Excel's QUARTILE.INC, which is also R's default, or QUARTILE.EXC, so results match the software your course uses. Runs 100% locally in your browser with zero server file uploads.
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- School & study tools
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Separate numbers with commas, spaces, or new lines; paste a column from a spreadsheet as it is.
Centre and spread
The mean is the total divided by the count; the median is the middle value once the numbers are sorted, or the average of the two middle values; the mode is the most frequent value. When a few extreme values pull the mean away from where most of the data sits, the median describes the typical value better.
Standard deviation measures how far values typically sit from the mean, in the same units as the data; variance is its square. The standard error of the mean, the sample standard deviation divided by the square root of the count, describes how precisely the sample mean estimates the population mean.
Quartiles and outliers
Quartiles split the sorted data into four parts. Small samples have no single correct way to place them between values, which is why software disagrees: the inclusive method, used by Excel's QUARTILE.INC and R by default, and the exclusive method of QUARTILE.EXC give different answers for small lists. Choose the one your course or software uses.
Values more than 1.5 interquartile ranges beyond the quartiles are flagged as possible outliers, the rule boxplots use. For percentages and changes, the percentage calculator shows each step.
How to use it
- Paste or type the numbers, or copy a column from a spreadsheet.
- Choose how quartiles are calculated, if it matters for your course.
- Read every summary statistic, with the sorted list below.
Privacy & limitations
Your numbers stay in your browser; nothing is sent or stored.
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Frequently asked questions
Sample or population standard deviation?
Use the sample standard deviation (dividing by n − 1) when the numbers are a sample from a larger group, which is the usual case. Use the population version (dividing by n) only when the numbers are the whole group you care about. Excel calls them STDEV.S and STDEV.P.
Why do quartiles differ between calculators?
There are several accepted ways to take quartiles from a small sample. Inclusive (Excel QUARTILE.INC, R's default) and exclusive (QUARTILE.EXC) are the two most common; for 1 to 10, Q1 is 3.25 inclusive and 2.75 exclusive.
What counts as an outlier?
The page flags values more than 1.5 times the interquartile range below the first quartile or above the third, Tukey's rule. It is a prompt to check the value, not proof that it is wrong.
What if no number repeats?
Then there is no mode. When several values share the highest count, all of them are modes.
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