Five-Number Summary Calculator
Find the minimum, Q1, median, Q3, and maximum of a data set, plus the interquartile range.
Quartiles use linear interpolation between the closest ranks (the type-7 method, the same one spreadsheets use for PERCENTILE.INC).
How it works
The five-number summary boils a data set down to five landmarks: the smallest value, the first quartile (Q1), the median, the third quartile (Q3), and the largest value. Together they sketch where the data sits and how it spreads.
This tool sorts your numbers, then finds each quartile by linear interpolation between ranks — the type-7 method spreadsheets use for PERCENTILE.INC. It also reports the interquartile range, Q3 minus Q1, which measures the spread of the middle half.
These five numbers are exactly what you need to draw a box plot, and because the median and quartiles ignore the tails, the summary holds up well even when a stray high or low value would throw off the mean.
Frequently asked questions
What is a five-number summary?
It's the minimum, first quartile, median, third quartile, and maximum of a data set. Those five points describe the center, the spread, and the extremes at a glance.
Which quartile method does this use?
Linear interpolation between the closest ranks — the type-7 method, the same one behind a spreadsheet's PERCENTILE.INC. Other conventions (like Tukey's hinges) can shift Q1 and Q3 slightly on small samples.
How is the IQR related to the summary?
The interquartile range is simply Q3 minus Q1, the width of the middle 50% of your data. It's the spread measure a box plot's box represents.