Also known as a Bar Mekko Chart, Cascade Chart, Variwide Chart, Area Bar/Column Graph.

A Variable Width Bar Chart is a type of graphical representation that differs from traditional Bar Charts in that the width of each bar carries significant meaning. Rather than all bars being of uniform width, as in conventional bar charts, the width of the bars in a Variable Width Bar Chart is determined by an additional dimension within the dataset.

In essence, each bar in the chart can represent a specific category, such as different product lines or demographic groups. Variable Width Bar Charts can be oriented either vertically or horizontally, depending on the preference and the nature of the data.

The lengths of all the bars are proportional to a variable with discrete data, like in a typical Bar Chart. However, the widths of the bars are not arbitrary and are proportion to another variable in relation to its total. In other words, the widths are always visualising percentages and the part-to-a-whole relationship in that variable.

Variable Width Bar Charts are particularly useful when visualising data where the width of the bars provides meaningful context or insight into the underlying dataset. They can be used in scenarios such as comparing the profitability of different product lines, illustrating demographic distributions, or analysing sales volume and profit margins.

Tools to generate a Variable Width Bar Chart with:
The R Graph Gallery
Tableau