Sankey Diagram Maker

About the Sankey Diagram Maker

A Sankey diagram shows how amounts flow from one stage to the next — income into a budget and out to rent, food and savings; visitors from search and social media through a website to a purchase; energy from its sources to its uses and losses. Each flow is a band whose width is proportional to its amount, so the big flows stand out at a glance.

Type one flow per line as Source [Amount] Target (the format SankeyMATIC uses, with [*] for “whatever is left”), paste a table of source, target and amount columns, or paste one row per person or item with a column per stage for an alluvial diagram. Labels show each node’s amount and its share of the total, colours follow the source or the target of each flow, and the layout keeps crossings few. Everything is drawn in your browser.

Common uses

• Showing where a monthly or yearly budget goes, from every income to every expense and saving.
• Website, app or sales funnels: where visitors come from, where they leave and how many buy.
• Energy, water or material balances: sources, uses and losses.
• Customers or students moving between plans, classes or grades from one year to the next (alluvial).
• Turning a table of from–to–amount rows into a picture for a report or slide.

The line format

One flow per line: the source node, the amount in square brackets, the target node — Salary [4200] Budget. Node names may contain spaces, digits and emoji, and the same name on several lines is the same node, so flows join up (names are case-sensitive: “Rent” and “rent” are two nodes).

• [*] — the flow takes whatever its source has left after its other flows; [?] — it brings whatever its target still needs. A result below 0 is counted as 0, and the flow is left out.
• A colour after the target paints that flow: Budget [600] Food #E69F00, with an opacity after a dot: #E69F00.7.
• :Savings #009E73 colours a node; add >> to paint its outgoing flows or << for its incoming ones.
• Lines starting with // are comments.

This is the syntax of SankeyMATIC, so diagrams typed there can be pasted here; the settings and moved nodes that SankeyMATIC adds to its text are left out (with a note), and the look is chosen with the options on this page.

Tables and alluvial stages

A flow table has a source column, a target column and an amount column; columns named Source/From, Target/To and Value/Amount/Count are found by themselves, and three unnamed columns are read in that order. Rows with the same source and target are added together, and a table without an amount column counts each row as 1.

For an alluvial diagram, give each stage its own column and each person, customer or item its own row (or add a count column). Values are drawn per stage, so “Basic” last year and “Basic” this year are separate nodes with the same colour. When a table repeats the same names in its first two columns, it is drawn this way automatically.

How the diagram is laid out

Nodes are placed in columns by the longest chain of flows that leads to them; with Justify, nodes with no outgoing flows move to the right-hand edge, while Left keeps each node right after its sources (good for funnels with exits at every step). Node heights use one scale for the whole diagram, so equal amounts are equally tall, and a node is as tall as the larger of what flows in and what flows out.

With Order: Fewer crossings, the tool then moves each node a few times towards the middle of the nodes it is linked to and pushes overlapping nodes apart; As in the data keeps your order, and Largest first sorts each column. Flows leave and enter each node in the order of the nodes at their other end. Labels that would overlap are left out (with a note), and an amount is never cut short: where it has no room, the label shows the shorter form (the amount without its share) or the name alone. Hover over a node or flow in the diagram to read its amount; the table under the diagram has every node’s totals.

Percentages and imbalances

The total is everything that flows out of the nodes nothing flows into — all incomes in a budget, all visitors in a funnel, all rows of an alluvial diagram — and every share is a node’s amount divided by it. When a node receives more than it sends on (or the other way round), the tool says which one and draws it at its larger amount; add a flow, or use [*] or [?], to show the difference.

Limitations

• Flows cannot go round in a loop (Budget → Savings → Budget): give the node a second name for its second appearance, such as “Budget (next month)”.
• With three or more alluvial stages, each pair of neighbouring stages is counted on its own: the diagram shows how many go from each value to the next, not the whole path of every row.
• Up to 300 nodes and 3,000 flows; amounts must be greater than 0. Flows are drawn as bands of one colour (no gradients).
• Tables of up to 10,000 rows (of a file, its first 10,000 rows); for an alluvial diagram of more people or items, add a count column and one row per combination of values.
• Very small flows can be thinner than a pixel; they are drawn at least one pixel wide, so the widths of tiny flows are not to scale.

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