Box plot maker — quartiles and outliers
Paste data to create a box plot and calculate the five-number summary, IQR, Tukey whiskers and observations beyond the whiskers. Download the result as SVG or CSV.
All calculations stay in your browser.
How do I use this page?
- Paste numbers or choose a prepared example.
- Select Calculate and compare quartiles, IQR, whiskers and outlying points.
- Download the SVG plot or CSV table for further analysis.
Method, example and limitations
Quartiles use R7 interpolation: the zero-based position is h = (n − 1)p. When h is not an integer, the result is linearly interpolated between adjacent ordered observations.
IQR = Q3 − Q1. Tukey's lower and upper fences are Q1 − 1.5 IQR and Q3 + 1.5 IQR. Whiskers end at the extreme observations within those fences; points beyond them are potential outliers rather than automatic errors.
A long box or unequal whiskers may indicate high spread or skew. The plot does not replace the data table: different observation patterns can share the same box plot.
For 2; 4; 4; 6; 9; 12; 15; 100, R7 gives Q1=4, Q2=7.5 and Q3=12.75. IQR=8.75, so the upper Tukey fence is 25.875; 100 lies beyond the whisker and is drawn separately.