Type a Sankey diagram, don't draw it
A Sankey diagram is a picture of numbers. Draw it by hand, in a slide tool or a whiteboard app, and the picture and the numbers start to drift the moment someone edits either. Keep the numbers in a table and draw the picture from them, and the two cannot disagree.
A drawn band is a claim nobody checks
In a hand-drawn Sankey, a band's width is whatever the author dragged it to. Nothing ties it to the amount it is meant to show, so a band labelled 300 can be drawn as wide as one labelled 500, and the reader, who compares widths, not labels, takes away the wrong story.
A table is checkable
Put the same diagram in a table, one row per node with where it flows and how much, and every claim can be checked. The widths come from the numbers. The totals can be added up. A node whose outflow exceeds its inflow stands out, because the editor computes the difference instead of hoping someone notices.
Changes are one cell, not one redraw
Budgets get revised, funnels get re-measured, energy balances get corrected. With a drawn Sankey, each change means moving bands, re-routing curves and re-checking that everything still lines up. With a typed one, you change the number, and the diagram re-lays itself out around it.
Start from data you already have
Most Sankey data already exists as a spreadsheet: a source, a target and a value per row. That table pastes straight into SankeyCharts.app, which turns each distinct name into a node and each row into a flow. If your data is not in that shape yet, QueryChart's guide to preparing it walks through the reshaping.
Try it on your own numbers
The editor is free and opens with a starter Sankey diagram. One row per node, and the diagram draws itself as you type. No signup required.
Create Your Sankey Diagram Free