Size

The Size property allows you to encode data by assigning different sizes to the marks in a data view. Depending on whether you use a discrete or continuous field, you will add either categorical or quantitative size encodings.

Categorical Sizes

When you place a discrete field on the Size target on the Marks card, Tableau separates the marks according to the members in the dimension, and assigns a unique size to each member. Because size has an inherent order (small to big), categorical sizes work best for ordered data like years or quarters.
Size-encoding data with a discrete field separates the marks in the same way as the Detail property does, and then provides additional information (a size) for each mark. When you add categorical size encoding to a view, Tableau displays a legend showing the sizes assigned to each member in the field on the Size target. You can modify how these sizes are distributed using the Edit Sizes dialog box.

1. Double-click the legend or select Edit Size from the legend’s menu.
   
2. In the Edit Sizes dialog box, sizes are displayed on the left and a size range slider is shown on the right. The sizes assigned to each member are distributed across the specified range. Use the slider to adjust the sizes assigned to each member.
   You can also select Reversed to assign the largest mark to the smallest value and the smallest mark to the largest value.
   
   
3. When finished, click OK.
   

The view below shows profit and order quantity broken out by region and order date. The order priority is indicated by the size of the mark.

Quantitative Sizes

When you place a continuous field on the Size target, Tableau draws each mark with a different size using a continuous range. The smallest value is assigned the smallest sized mark and the largest value is represented by the largest mark.
When you add quantitative size encoding to the view, Tableau displays a legend showing the range of values over which sizes are assigned. You can modify how these sizes are distributed using the Edit Sizes dialog box.

1. Double-click on the size legend or select Edit Size from the legend’s menu to open the Edit Sizes dialog box.
   
2. Select one of the following ways to map the sizes:
   
   • Automatically - Selects the mapping that best fits your data. If the data is numeric and does not cross zero (all positive or all negative), the ‘From zero’ mapping is used. Otherwise, the ‘By range’ mapping is used.
     
   • By range - Uses the minimum and maximum values in the data to determine the distribution of sizes. For example, if a field has values from 14 to 25, the sizes will be distributed across this range.
     
   • From zero - Sizes are interpolated from zero, assigning the maximum mark size to the absolute value of the data value that is farthest from zero.
     
   
   
3. Use the range slider to adjust the distribution of sizes. When the From zero mapping is selected, the lower slider is disabled because it is always set to zero.
   
4. Select Reversed to assign the largest mark to the smallest value and the smallest mark to the largest value. This option is not available if you are mapping sizes from zero because the smallest mark is always assigned to zero.
   
5. To modify the distribution of sizes, select the Start value for range and End value for range checkboxes and type in beginning and end values for the range.
   
6. When finished, click OK.
   

The view below analyzes the time it takes to ship products based on their ship mode, order date, and the size of order. The size of each mark represents the order quantity while the color represents the ship mode. You can see that most products ship within one or two days. However, larger orders shipped via Regular Air tend to take longer, especially during the second quarter. Curiously, there are a couple of smaller orders that were shipped via Express Air that took a long time to ship.

You can also change the size of the marks using the Size slider on the Size drop-down control.

The Size slider affects different marks in different ways, as described in the following table.

Mark Type	Description
Circle, Square, Shape, Text	Makes the mark bigger or smaller.
Bar, Gantt Bar	Makes bars wider or narrower.
Line	Makes lines thicker or thinner.
Polygon	You cannot change the size of a polygon.
Pie	Makes the overall size of the pie bigger and smaller.

The size of your data view is not modified when you change marks using the Size slider. However, if you change the view size, the mark size might change to accommodate the new formatting. For example, if you make the table bigger, the marks might become bigger as well.