About this five number summary calculator
The five number summary describes a distribution with minimum, first quartile, median, third quartile and maximum, exactly what a box plot draws. For 12, 7, 9, 12, 15, 3, 8 it is 3, 7, 9, 12, 15: the box runs from 7 to 12 with a line at 9, and the whiskers reach 3 and 15.