Tableau Histograms and Box Plots

Bar and line charts compare totals. Histograms and box plots go further and show how values spread. They answer questions such as "Do most orders cost little, or do a few orders cost a lot?"

Histograms

A histogram groups numbers into ranges called bins and counts how many records land in each bin. Imagine sorting coins into jars by size. Each jar is a bin, and the coin count in each jar is the bar height.

Orders by Sales Range
Count
  |  ###
  |  ###  ###
  |  ###  ###  ###
  |  ###  ###  ###  ###        ###
  +--0-100-200-300-400-500-...-1000-->
          Sales Bins

Create a Histogram

1. Click the Sales measure in the Data pane.
2. Open Show Me and choose Histogram.
3. Tableau creates a bin field named Sales (bin) and counts records for each bin.

Change the Bin Size

Right-click Sales (bin) in the Data pane and choose Edit. Enter a new Size of Bins value, such as 100. Small bins show fine detail, and large bins show broad patterns. Experiment until the shape of the data appears clearly.

What the Shape Tells You

• Tall bars on the left, thin tail on the right: Most orders are small, and a few are large.
• Symmetric bell shape: Values cluster around an average.
• Two separate peaks: The data holds two different customer groups.

Box Plots

A box plot, also called a box-and-whisker plot, summarizes a distribution with five key numbers. A single box plot replaces dozens of data points and lets you compare groups side by side.

        Outlier
           o
           |  <-- Upper whisker
        +-----+
        |     |  <-- Third quartile (75%)
        |-----|  <-- Median (50%)
        |     |  <-- First quartile (25%)
        +-----+
           |  <-- Lower whisker

Read the Parts

• Box: The middle half of the data sits inside the box.
• Median line: Half the values fall above this line and half fall below.
• Whiskers: Lines extend to the lowest and highest normal values.
• Outliers: Dots beyond the whiskers mark unusually high or low values.

Create a Box Plot

1. Drag Category to Columns.
2. Drag Sales to Rows.
3. Drag Customer Name or Order ID to the Detail mark on the Marks card so Tableau plots one point per record.
4. Open Show Me and choose Box-and-Whisker Plot.

Each category now shows its own box. A tall box means wide variation. A short box means consistent values.

Adjust the Whiskers

Right-click the axis and choose Edit Reference Line. Change the whisker setting from the default to the minimum and maximum values or a custom range. The standard setting extends whiskers up to 1.5 times the box height.

Choose Between the Two Charts

Question                          | Best Chart
-------------------------------------------------
How many orders fall in each range? | Histogram
Which group has more variation?     | Box plot
Where do outliers hide?             | Box plot
What shape does the data take?      | Histogram

Practical Use Cases

• Delivery managers compare shipping times across regions with box plots.
• Retail analysts study price spread with histograms.
• Teachers view exam score distributions to spot unusual results.

Summary

Histograms count records inside bins and reveal the shape of data. Box plots condense a distribution into quartiles, whiskers, and outliers. Use histograms to study one measure in depth, and use box plots to compare groups quickly.