Flow value
The flow value is the amount a link carries: euros, megawatt-hours, visitors, tonnes. It is the number behind the picture, because a Sankey diagram draws every link as wide as its value. Get the values right and the diagram cannot mislead; get one wrong and a band is drawn too wide or too thin for everyone who reads it.
Make your Sankey diagram now, no signup required
Open the editor and type your nodes one per row, with where each one flows and how much. The diagram draws itself as you type. Your work is saved automatically in your browser.
Create Your Sankey Diagram FreeOne unit per diagram
Widths can only be compared when every value is in the same unit. A diagram that mixes euros and dollars, or kilowatt-hours and megawatt-hours, draws bands whose widths mean nothing next to each other. SankeyCharts.app keeps one unit per chart: type it with a number ("€1500", "1500 GWh") and the whole chart takes it, and a value in a different unit is refused rather than drawn wrong.
Balance
On a node that amounts pass through, the values arriving should add up to the values leaving. When they don't, the difference is either a real loss the diagram should show as its own link (waste, churn, tax) or a mistake in the data. The editor reports the difference on the node, in the chart's unit, so you can decide which it is.
Zero, missing and negative values
A Sankey can only draw positive amounts. A link with no value has no width (SankeyCharts.app draws it dashed until it gets one), and a negative value has no meaning as a band: show it as a flow in the opposite direction, or as its own node, such as "Refunds".
Frequently asked questions
What does the value of a Sankey flow mean?
The amount the flow carries, in the diagram's unit. It sets the band's width, so it is the number the reader is really comparing.
Can a Sankey diagram use percentages?
Yes, as long as every value is a percentage of the same total. Mixing percentages with absolute amounts makes the widths incomparable.
Why don't my Sankey values add up?
Usually a missing link or a typo. If the gap is real (waste, churn, fees), add it as its own link to an end node so the diagram shows it.
Ready to draw your first flow?
The editor opens with a starter Sankey diagram. Type your own nodes and amounts, and the diagram rebuilds itself as you type. No signup required to get started.
Create Your Sankey Diagram Free