Statistics Calculator
Paste in a list of numbers and get mean, median, mode and standard deviation together — the four summary numbers that describe a data set's centre and spread without opening a spreadsheet.
Inputs
Result
Mean 18
Median 15.5 · Std dev 12.3153 · Count 6 · Range 4–42
Visual breakdown
How the statistics calculator works
Mean is the sum divided by the count — the arithmetic average.
Median is the middle value once sorted; with an even count, it's the average of the two middle values.
Standard deviation measures typical spread from the mean: it's the square root of the average squared distance of each value from the mean.
Worked example: 4, 8, 15, 16, 23, 42
- Mean = (4+8+15+16+23+42) ÷ 6 = 108 ÷ 6 = 18.
- Sorted: 4, 8, 15, 16, 23, 42 — median = (15+16) ÷ 2 = 15.5 (average of the two middle values, since there are 6 numbers).
- Standard deviation ≈ 12.1, reflecting that 42 pulls the spread up noticeably relative to the cluster of smaller numbers.
Common mistakes to avoid
Reading mean and median as interchangeable
They can differ a lot when a data set is skewed by outliers — the mean of 4, 8, 15, 16, 23, 42 is pulled upward by 42, while the median stays closer to where most of the data actually sits.
Expecting a single mode from data with no repeats
If every value in the list is unique, there is no meaningful mode — the calculator will still return a value, but with a repeat count of 1 it carries little statistical meaning.
Frequently asked questions
When should I trust the mean over the median, or vice versa?
The median is more robust to outliers — for skewed data like incomes or house prices, the median usually represents the 'typical' value better than the mean.
What does a low standard deviation actually indicate?
The data points cluster tightly around the mean; a high standard deviation means the values are spread widely, with some far from the average.
Does this calculate population or sample standard deviation?
It computes the population standard deviation (dividing by n), which is the appropriate choice when your data set is the entire group of interest rather than a sample drawn from a larger population.
How should I format the numbers I paste in?
Separate them with commas or spaces — the tool parses either format and ignores anything that isn't a valid number.
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