Step 1: Find the minumum.
The minimum is the far left hand side of the graph, at the tip of the left whisker. For this graph, the left whisker end is at approximately 0.75.
Step 2:Find Q1.
Q1 is represented by the far left hand side of the box. In this case, about 2.5.
Step 3: Find the median.
The median is represented by the vertical bar. In this boxplot, it can be found at about 6.5.
Step 4: Find Q3.
Q3 is the far right hand edge of the box, at about 12 in this graph.
Step 5: Find the maximum.
The maximum is the end of the “whiskers”: in this graph, at approximately 16.