Sankey Diagram Maker
Visualise a flow between stages as a Sankey diagram - free, no signup.
What this tool does
Enter one flow per line as source, target, value - for example 'Website Visits, Signed Up, 500' - and this works out the stages automatically from how the flows connect, then draws a Sankey diagram: each stage as a bar, sized by its total flow, connected by bands whose width shows how much moves between them. It's built for exactly the question a Sankey diagram answers - where does a total split, merge or drop off as it moves through a process.
Draws a Sankey flow diagram from a simple source, target, value list you paste or type - no manual layout or stage positioning needed.
Works out which stage comes before which automatically from the flow connections, and sizes each stage's bar in proportion to its total flow.
Draws flow bands with width proportional to value, so the biggest drop-offs or contributions are visually obvious.
How to use it
- Enter one flow per line as source, target, value.
- Add a chart title if you want one, and pick a colour palette.
- Export as PNG or SVG.
Why use this chart maker
Sankey diagrams show flows between stages, such as money, energy or traffic. Writing source, target and value lines is easier than drawing the flows.
Why we built it
We built the Sankey diagram maker to work out the stage order from how the flows connect, with no separate column setup. Show drop-off with the funnel chart maker and shares with the stacked bar chart maker.
Who this tool is for
- Analysts showing flows of money, users or energy
- Marketers mapping customer journeys
- Students
When to use it
- Budget or energy flows.
- User journeys.
- Supply chains.
- Reports and presentations.
What a Sankey diagram is for
Where a total splits, merges, or leaks, as it moves through stages.
A Sankey diagram is the right chart when you have a quantity flowing through a sequence of stages and want to see how it divides at each step: website visitors splitting into signups and bounces, a budget dividing across departments and then sub-categories, or energy input splitting into useful output and losses. The width of each flow band is proportional to its value, so the eye reads the biggest movements immediately, in a way a table of the same numbers doesn't communicate as quickly.
Stage order (which column each named stage appears in) is worked out automatically from the flow connections themselves - a stage that only appears as a source starts in the first column, and everything else is placed one column further along than whatever feeds into it. You don't need to specify stage order separately from the flows.
What you give it, and what you get back
| Item | Details |
|---|---|
| Input | Source, target and value lines. |
| Output | A diagram with stages placed automatically and widths proportional to values. |
| Export | Save the chart. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Diagram looks tangled | There are many links. | Reduce links or combine small flows. |
| A loop appears | Cycles cannot be drawn meaningfully. | Break the loop. |
| A row is skipped | It does not match the expected format. | Check the message listing unreadable lines and fix them. |
Assumptions and limitations
- This lays out stages automatically from the flow connections - if your data contains a genuine loop (A feeds B which feeds back into A), it won't crash, but the diagram won't represent a true cycle meaningfully, since a Sankey diagram is built for one-directional flow.
- Works best with a reasonable number of flows and stages; a very large or densely connected diagram becomes visually crowded rather than automatically simplifying.
- The chart is drawn as SVG and exported to PNG at a fixed resolution suited to slides and documents, not large-format print.
Frequently asked questions
How do I make a Sankey diagram online for free?
Enter one flow per line as source, target, value, and the diagram draws instantly with stages worked out automatically. Download it as a PNG or SVG with no signup and no watermark.
How are the stages (columns) decided?
Automatically, from how the flows connect - a stage that only appears as a source starts in the first column, and every other stage is placed one column further along than whatever feeds into it.
What does the width of each flow band mean?
It's proportional to that flow's value, so a wider band represents a bigger movement between two stages - the biggest drop-offs or contributions are visible at a glance.
Can I use this for a budget breakdown?
Yes - enter each allocation as source, target, value (for example 'Total Budget, Marketing, 25000'), and it draws exactly the same way as a traffic or process flow.
What happens if my data has a loop in it?
The diagram won't crash, but a genuine loop isn't something a Sankey diagram represents meaningfully - it's built for one-directional flow between stages, not cyclical processes.
Is my data uploaded anywhere?
No. The diagram is drawn entirely in your browser using the data you type or paste - nothing is sent to a server, and closing the tab clears it.