Free Online Alluvial Diagram Maker

Visualize how categories regroup and flow across multiple dimensions. Track shifts, migrations, and transitions.

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What Is a Alluvial Diagram?

An alluvial diagram is a flow visualization that shows how categorical data regroups across multiple dimensions or time points. Smooth, flowing bands connect categories on parallel vertical axes, with band width proportional to the quantity moving between groups. Unlike Sankey diagrams that focus on directional flow through a process, alluvial diagrams emphasize how membership in categories shifts across stages. Each vertical axis represents a dimension or time snapshot, and the bands weave between them to reveal patterns of stability and change. Color-coding bands by their origin or destination category makes it easy to trace where groups came from and where they went. The visual effect resembles a braided river, making complex transitions intuitive to read even for non-technical audiences.

What Data You Need for a Alluvial Diagram

You need one label column written as "Source > Target" (separators >, ->, or → all work) plus one numeric value column for the band width; for multi-stage diagrams chain rows stage-to-stage where a target becomes the next row's source. Example rows: "Trial > Paid" 320, then "Paid > Renewed" 210 forms the next axis. (Alluvial uses the same Sankey renderer.)

When to Use a Alluvial Diagram

Use alluvial diagrams whenever you need to track how items, people, or categories shift between groups across multiple stages. Common applications include voter migration analysis between election cycles, student major changes across academic semesters, customer segment transitions in cohort analyses, and employee role changes across organizational restructurings. They are also effective in healthcare for tracking patient pathways through treatment stages, in marketing for visualizing conversion funnel transitions, and in supply chain analysis for tracing product category shifts. Alluvial diagrams work best when you have three to six stages and a manageable number of categories at each stage, allowing the flowing bands to remain readable and the regrouping patterns to emerge clearly.

Where a Alluvial Diagram Works Best

Cohort retention across months — show how a signup cohort splits into Active, Dormant, and Churned at 30/60/90 days, with band width revealing where the biggest drop-off happens.
Survey response shifts — track how the same respondents move between answer choices (Agree→Neutral→Disagree) across two waves of a study.
Customer plan migration — visualize upgrades, downgrades, and cancellations between Free, Pro, and Enterprise tiers quarter over quarter.
Student pathway tracking — follow a class from declared major through internship field into first job category to expose where intentions and outcomes diverge.

Alluvial Diagram Example: Voter Transition 2020 → 2024

An analyst tracks how voters moved between parties across two elections.

Sample data: "Source > Target" labels + value: Dem > Dem 410; Dem > Rep 55; Rep > Rep 380; Rep > Dem 70.

Most voters stayed loyal (410 Dem→Dem, 380 Rep→Rep); the cross-flows (55, 70) are the swing that decides the race.

How to Create a Alluvial Diagram Online

Step 1: Open ChartLoad and select Alluvial Diagram from the chart type menu
Step 2: Define your stages or dimensions as parallel vertical axes with category labels
Step 3: Enter the flow quantities that move between each category pair across stages
Step 4: Assign colors to bands by origin category to make individual flows easy to trace
Step 5: Adjust band opacity and curvature to balance visual clarity with aesthetic appeal
Step 6: Export the finished alluvial diagram as PNG, PDF, or SVG for presentations

Alluvial Diagram Best Practices & Tips

Keep the number of categories per column to 5-8 for clarity — more creates a web of crossing flows.
Use consistent colors for categories that persist across columns so readers can track them through the flow.
Alluvial diagrams show how group memberships change across stages, time periods, or classification systems.
Wider ribbons represent larger flows — label them with exact counts or percentages for precision.
Place the most important categorical variable at the leftmost column to anchor the viewer's reading direction.
Use a tooltip on each ribbon to show the exact count of items flowing from one category to the next.
Alluvial diagrams are named after alluvial fans — geological formations where rivers spread into branching channels.

Common Alluvial Diagram Mistakes to Avoid

Letting the two sides of a stage sum to different totals — if outgoing bands from 'Paid' don't equal incoming bands to the next axis, ribbons get clipped or float, breaking the flow illusion.
Using too many thin slivers: 30+ tiny bands turn the diagram into spaghetti. Bucket categories under ~2% of the total into an 'Other' lane before plotting.
Reordering categories on each axis automatically — auto-sorting minimizes crossings but scrambles a meaningful order (e.g., grade levels or time), so lock the axis order when sequence matters.
Treating it like a Sankey for a process with loops — alluvial axes are strictly left-to-right stages, so feedback or recycled flows can't bend backward and will be misread.

Frequently Asked Questions

How is an alluvial diagram different from a Sankey chart?

Both show flows, but alluvial diagrams emphasize categorical regrouping across parallel axes, while Sankey charts focus on directional flow quantities through a process.

Can I show more than two stages?

Yes — add as many stages (dimensions) as needed to track transitions across multiple time points or categories.

How do I read the bands?

Each band connects a category in one stage to a category in the next. The band width represents the quantity flowing between them.

Related Chart Types

Ready-Made Alluvial Diagram Templates

Skip the blank canvas — open a free, editable Alluvial Diagram template, swap in your own data, and export. Browse all templates.

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