Sankey Cash Flow Diagram

Sankey diagrams encode quantity as width. Income enters on one side, splits through taxes and categories, and arrives at destinations on the other, with every branch sized in proportion to the amount flowing through it. Matthew Sankey drew the first one in 1898 to show energy losses in a steam engine, and the form still suits anything that divides and subdivides.

The advantage over a pie chart is that it shows the splitting, not just the shares. A pie can tell you food was 12% of spending. A Sankey shows gross income narrowing to take-home, then take-home dividing, so the tax wedge and the savings branch appear on the same picture at the same scale.

Comparison is what the eye does well here. Two streams of similar width are similar amounts, and that reads instantly in a way two numbers in a table do not, particularly when the categories are ones nobody thinks to compare.