Mermaid for
Sankey diagrams
Show where everything flows
Visualize how budgets, users, energy, or traffic move and split across a system, with each flow drawn to scale.
What is a Sankey diagram?
A Sankey diagram shows how a quantity flows from one set of nodes to another. Each link is drawn as a band whose width is proportional to its value, so the largest flows and the biggest losses are visible at a glance.
The format is named after Matthew Henry Phineas Riall Sankey, an Irish engineer who used it in 1898 to show the energy efficiency of a steam engine. It is now common in energy analysis, finance, operations, and product analytics. In Mermaid, a Sankey diagram is written as CSV: each line is a source, a target, and a value. You can paste rows from a spreadsheet and Mermaid draws the diagram.
What you can map
with a
Sankey diagram
User funnel and conversion analysis
Energy and resource flow visualization
Budget allocation and spend tracking
Traffic and referral source breakdowns
Supply chain and material flow
Revenue by segment or channel
Data pipeline volume tracking
User funnel and conversion analysis
Energy and resource flow visualization
Budget allocation and spend tracking
Traffic and referral source breakdowns
Supply chain and material flow
Revenue by segment or channel
Data pipeline volume tracking
Who uses Sankey diagrams
on Mermaid
Business Analysts
Map where resources, budget, or users go, and where the largest drop-offs happen.
Consultants
Show clients where value is being created or lost across a process.
When a Sankey diagram is
the right call
Traffic by source flowing into signups, trials, and paid conversions — showing drop-off at each stage.
Total budget flowing into headcount, infrastructure, marketing, and operations — with sub-breakdowns per category.
Total energy input distributed across heating, cooling, lighting, and equipment — with waste flows included.
Gross revenue flowing through direct, partner, and self-serve channels into each customer segment.
Less time syncing, more time building
One shared canvas for mapping ideas, collaborating live, and keeping teams on the same page, literally.
FAQ
Common questions about building Sankey diagrams in Mermaid.
