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Statistics Calculator
Mean, median, mode, range and standard deviation for a data set. Everything happens on this page, in your browser — nothing you enter is sent anywhere.
Two standard deviations are shown because courses disagree: the population version treats your list as the whole story, the sample version treats it as a sample of something bigger and divides by n−1 instead of n.
How this tool works
A list of numbers becomes information when it is summarised: a centre (mean, median or mode), a spread (range, standard deviation), and a count. This calculator produces the standard school set from raw data, so a page of test scores turns into a story about a class in seconds.
Using it, step by step
- Type or paste your numbers with commas or spaces between them — scores, times, heights, anything measured.
- Read the mean and median together: when they differ noticeably, a few extreme values are pulling the mean, and the median is the fairer centre.
- Use standard deviation as 'typical distance from the mean' — small means consistent, large means scattered.
- For class data, try removing the highest and lowest value and watch which summaries move; that sensitivity is itself examinable.
Where it stops
The mode reported is the most frequent value; data with every value appearing once honestly has none, and the page says so. For grouped or frequency-table data, the formulas differ — enter raw values here, not class intervals.