Categorical data flowing across multiple time periods or steps. Tracks group membership.
A free, animated alluvial flow diagram you can read here or embed on any website, from Scrollchart.
Alluvial Flow Diagram
An alluvial diagram tracks how members of a population redistribute across categories at each successive time point or stage. Each vertical column represents one time step; the stacked rectangles within it are the categories; and the flowing bands connecting adjacent columns show what fraction moved from one category to another.
The width of every band is proportional to the number of individuals making that particular transition. A fat band from category A at time 1 to category B at time 2 means many people switched; a thin band means few. Bands that stay within the same category are drawn as smooth, nearly-horizontal flows, making stability easy to spot against the crossing bands that signal churn.
Start at the leftmost column and note the relative sizes of the category blocks: they represent the initial composition of the population. Then follow the bands rightward. Bands that cross (rather than flow straight across) represent people changing category between steps.
At each column, the total height of all incoming bands equals the total height of that column's blocks, so nothing is created or lost. If a category block shrinks between columns, more people left it than arrived. Conversely, a growing block means net inflow. Look for consistent "exit" patterns (one category losing to the same destination repeatedly) versus one-time jumps that reverse in the next step.
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Source & accuracy
This alluvial flow diagram is an editorial illustration built to represent the concept accurately. Where it shows figures, they are typical or representative values chosen to make the relationship clear, not a single underlying dataset. The diagram and its explainer are reviewed and maintained centrally, and updated over time as understanding improves.
Tracking categorical membership across time
An alluvial flow diagram shows how individuals or groups move between categories over time. Each vertical slice represents a time period, and groups are stacked at each step. Flows between consecutive periods show which entities stay in their category and which transition. The width of each flow band encodes the count, making it easy to spot when a category shrinks, grows, or gains or loses members.
When to use alluvial instead of stacked area
Unlike a stacked bar chart, which shows totals, an alluvial diagram emphasizes movement and switching. If you care about aggregate proportions over time, stacked bars are clearer. If you want to see whether individuals are entering or leaving a cohort, or which categories act as sources vs sinks, alluvial reveals that structure. Election voting shifts, career path changes, and disease progression are natural alluvial subjects.
Embed this diagram
Add this animated alluvial flow diagram to your own site. Copy one line of HTML, or use the embed builder for theme and sizing options.
Reference
What this is
A free, embeddable, animated alluvial flow diagram for any website.
Who uses it
Data journalists, Researchers & academics, Content marketers, News organizations.
How to embed
Copy one line of HTML. No signup. No watermark. Works in WordPress, Webflow, Ghost, Substack, plain HTML.
File size
iframe embed, ~80 KB gzipped (loads on demand, does not block your page paint).
License
Free forever. Editorial explainer text included; updated centrally over time.
Copy the universal HTML snippet, the WordPress shortcode, or an iframe fallback -
see the WordPress plugin page for details. Any format keeps
the same Core Web Vitals profile and the same explainer text.
By embedding, you acknowledge the diagram and explainer text are served from scrollchart.com and may be updated from time to time to reflect new research or to link to relevant sources within the explainer.
Frequently asked questions
Where can I get a free animated "Alluvial Flow Diagram" for my website?
Scrollchart provides "Alluvial Flow Diagram" as a free, embeddable animated diagram you can add to any website with one line of HTML. No signup is required and there is no watermark. The diagram and its explainer text are served from scrollchart.com, so the embed stays current without any maintenance on your end.
How do I embed a alluvial flow diagram in a blog post or article?
Paste the one-line HTML snippet from the Scrollchart diagram page into your post editor. It works in WordPress, Webflow, Ghost, and plain HTML with no plugin required. The animated diagram and its explainer text load from scrollchart.com and render directly in your page DOM.