Sankey Diagram Maker Online

Visualize flows and transfers with a Sankey diagram. Show how quantities move between different stages or categories in a process.

Flow Data

Enter flow data as comma-separated values (source, target, value), one per line

Chart Title

Node Width

Link Opacity

Show Labels

Diagram Preview

Sankey Flow Diagram

Flow Summary

Source A → Target B

27.8%

Source A → Target C

16.7%

Source B → Target D

22.2%

Target B → Target E

13.9%

Target C → Target E

19.4%

Total Flow180

Nodes (6)

Source A

In: 0Out: 80

Target B

In: 50Out: 25

Target C

In: 30Out: 35

Source B

In: 0Out: 40

Target D

In: 40Out: 0

Target E

In: 60Out: 0

About Sankey Diagrams

Sankey diagrams visualize flows and transfers between nodes. The width of each link is proportional to the flow quantity. They are commonly used for energy flow, material flow, cost breakdown, and website traffic analysis.

How the Sankey Diagram Generator Works

This tool creates Sankey diagrams—flow visualizations that show quantities moving between nodes. Enter your flow data, customize colors and labels, and generate a professional diagram instantly.

Sankey diagrams use arrow width proportional to flow quantity. Thick arrows represent large flows; thin arrows show small flows. This makes it easy to spot major pathways and bottlenecks at a glance.

Input data as pairs: source node, target node, and flow value. The generator arranges nodes automatically to minimize crossing flows. Export as PNG or SVG for presentations, reports, or publications.

When You'd Actually Use This

Visualizing energy or material flows

Track energy from sources to end uses, or materials through a manufacturing process. Sankey diagrams reveal where most energy/material goes and where losses occur.

Mapping website user journeys

Show how users flow through your site—from landing pages to conversions. Identify drop-off points and popular pathways for UX optimization.

Analyzing budget allocations

Visualize money flowing from revenue sources to expense categories. Stakeholders instantly see where budget goes and can spot imbalances.

Tracking supply chain movements

Map products from suppliers through distribution to customers. Identify bottlenecks, single points of failure, and optimization opportunities.

Displaying migration or transfer data

Show population migration between regions, data transfers between systems, or customer churn between plans. Flow visualization reveals patterns tables hide.

Creating sustainability reports

Illustrate carbon emissions by source and sector, waste flows through recycling systems, or water usage across operations. Essential for ESG reporting.

What to Know Before Using

Flow conservation is key.Total flow into a node should equal total flow out (plus/minus any storage or loss at that node). Unbalanced flows confuse readers and indicate data errors.

Limit the number of nodes.Sankey diagrams get cluttered with too many nodes. Aim for 5-10 nodes max. Group smaller categories into "Other" to keep diagrams readable.

Order matters for readability.Arrange nodes logically—sources on left, destinations on right. Group related nodes together. Good layout reduces crossing flows and improves comprehension.

Color coding aids understanding.Use consistent colors for related flows. Differentiate categories clearly. Avoid similar colors that might confuse readers with color vision deficiencies.

Pro tip: Start with aggregated data, then drill down. Create a high-level Sankey first, then detailed diagrams for specific flows. This layered approach tells a clearer story.

Common Questions

What data format do I need?

Provide source, target, and value for each flow. Example: "Coal, Electricity Generation, 500" means 500 units flow from Coal to Electricity Generation.

Can I import data from CSV or Excel?

Yes, paste CSV-formatted data directly. Three columns: source, target, value. The tool parses and validates the data before generating the diagram.

What file formats can I export?

PNG for presentations and documents. SVG for editing in Illustrator or Inkscape. SVG scales infinitely without quality loss—best for publications.

How do I handle negative flows?

Sankey diagrams typically show positive flows only. For returns or reverse flows, create a separate arrow in the opposite direction with positive value.

Can I customize colors and styles?

Yes, choose colors for each node or flow. Adjust font sizes, arrow opacity, and diagram dimensions. Match your organization's branding guidelines.

What's the difference between Sankey and flow charts?

Flow charts show process steps and decisions. Sankey diagrams show quantities flowing between nodes. Sankey arrow width represents magnitude; flow chart arrows don't.

Who invented Sankey diagrams?

Named after Captain Matthew Sankey, who used them in 1898 for steam engine efficiency. They became standard in energy analysis and are now used across many fields.

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