English: Box plot of a small dataset (n = 20) with whiskers drawn by Tukey's rule: each whisker runs to the most extreme data value within 1.5 × IQR of the box, and values beyond that are plotted as outliers. The outlier is drawn as a filled point on the center line of the box. Each whisker end is labeled as the largest or smallest value inside the fences. The 20 data values are drawn as dots beside the box, with guides at the values that set each part of the plot. Dashed lines mark the fences, each labeled with the formula and value that set it: Q3 + 1.5 × IQR = 51 and Q1 − 1.5 × IQR = 3.

Data: 12, 15, 17, 18, 21, 21, 22, 24, 25, 26, 28, 29, 30, 31, 33, 33, 35, 38, 41, 58.

Q1 = 21, median = 27, Q3 = 33, IQR = 12, 1.5 × IQR = 18, lower fence = 3, upper fence = 51. Lower whisker = 12 (the minimum), upper whisker = 41 (the largest value at or below 51), one outlier = 58.

Quartiles: the dataset is chosen so that the common definitions agree. Tukey's hinges (median of each half), Hyndman and Fan type 7 (the R default) and type 6 (Minitab, SPSS) all give Q1 = 21 and Q3 = 33, because the 5th and 6th ordered values are equal (21) and so are the 15th and 16th (33).

A companion figure with whiskers to the minimum and maximum of the same data: File:Box plot with whiskers from minimum to maximum.svg.