Create a Box Plot

Create a Box Plot

A box plot summarizes a data set using the five-number summary: minimum, first quartile (Q1), median, third quartile (Q3), and maximum. The box shows the middle half of the data, and the whiskers extend to the smallest and largest values.

1) Order the data

List the data from least to greatest. This makes it easier to locate the center and quartiles.

2) Find the median

The median is the middle value. If there is an even number of data points, the median is the average of the two middle values.

3) Find Q1 and Q3

• Q1 is the median of the lower half of the data.
• Q3 is the median of the upper half of the data.

If the data set has an odd number of values, do not include the overall median in either half.

4) Identify the minimum and maximum

These are the smallest and largest values in the ordered data set.

5) Draw the box plot

Draw a number line, place points at the five summary values, then connect them:

• draw a box from Q1 to Q3,
• draw a line at the median inside the box,
• extend whiskers from the box to the minimum and maximum.

Check your work

Make sure the values are in order: minimum ≤ Q1 ≤ median ≤ Q3 ≤ maximum. Also check that the box contains the middle 50% of the data.