Flowchart Symbols: 20+ Shapes and Their Meanings

Flowchart symbols are the standard shapes that represent each step in a process: an oval starts and ends the flow, a rectangle marks an action, a diamond asks a question, and arrows connect them in order. Learn the handful that matter and you can read or draw almost any process diagram without a legend. This guide covers every symbol you will meet, what each one means, and when to reach for it.

The shapes trace back to a 1970 ANSI standard, later adopted as ISO 5807, so the same rectangle means the same thing whether you draw it in Visio, Miro, or a text-based tool. That shared vocabulary is why flowcharts sit next to a user flow diagram, a sequence diagram example, and a data flow diagram in most teams' documentation. If you are mapping a real workflow, our guide to process documentation examples shows where these charts fit.

Flowchart symbols cheat sheet

Before the detail, here is the reference table. These are the core flowchart symbols and meanings you will use in nine out of ten diagrams. Keep it open while you read the grouped sections below.

Basic flowchart symbols

These five shapes carry the meaning in most diagrams. Master them first, because every other symbol is a specialization of one of these ideas.

Terminator symbol

The terminator is an oval or rounded pill, and it marks where a process begins and ends. Every valid flowchart opens with a "Start" terminator and closes with an "End" one. You will sometimes see it drawn as a stadium shape. Whatever the exact curve, its job never changes: it signals the boundary of the flow, nothing more.

Process rectangle

A plain rectangle is the process symbol, the workhorse of any flowchart. It represents a single action or operation, such as "Send confirmation email" or "Calculate total." Each rectangle should hold one clear step. If you find yourself writing "and" inside a process box, split it into two boxes so the sequence stays readable.

Decision diamond

The diamond is the decision symbol, and it always poses a question with a branching answer. Most decisions are yes/no, so two arrows leave the diamond, each labeled with an outcome. Keep the question phrased so the answer is unambiguous: "Payment approved?" works, while "Check payment" does not. A decision diamond is the only common symbol with more than one exit arrow.

Input/output parallelogram

A parallelogram, the slanted four-sided shape, marks data moving into or out of the process. This is the input/output symbol. Use it when a user enters an order, a system reads a file, or a report gets generated. The parallelogram tells a reader that data crosses a boundary here, which separates real information flow from the internal actions a rectangle shows.

Flowline arrow

The flowline is the arrow that connects every other shape and sets the reading order. Without it, a diagram is just a scatter of boxes. Arrows should point in one consistent direction, usually top to bottom or left to right, and they should never cross where you can avoid it. A labeled flowline, like "Yes" or "No" off a diamond, tells the reader which branch each path represents.

A flowchart in real syntax

Reading shapes on their own is one thing. Seeing them wired together makes the pattern stick. Here is a small approval flow written in Mermaid, a text format that renders these exact symbols. The oval is the terminator, each rectangle a process, and the braces draw the decision diamond.

flowchart TD
    A([Start]) --> B[Submit expense report]
    B --> C{Amount under $500?}
    C -->|Yes| D[Auto-approve]
    C -->|No| E[Send to manager]
    E --> F{Manager approves?}
    F -->|Yes| D
    F -->|No| G[Reject and notify]
    D --> H([End])
    G --> H

Notice how the two decision diamonds each split into a "Yes" and "No" flowline, and how both the auto-approve and reject paths converge on the same "End" terminator. That is the whole grammar of a basic flowchart in nine lines of text.

Intermediate flowchart symbols

Once a process grows past a dozen steps, the basic five stop being enough. These shapes keep larger diagrams clean and let you reference work that lives elsewhere.

The connector is a small circle used to link two points without drawing a long, tangled arrow across the page. You put a lettered circle where a flowline would leave, then a matching circle where it should resume. Its cousin, the off-page connector, is a pentagon (home-plate shape) that means the flow continues on another page entirely, which is handy for a process that spans several printed sheets.

A document symbol is a rectangle with a wavy bottom edge, and it stands for a printed or written report the process produces, such as an invoice or a packing slip. When several documents pile up, the multi-document variant stacks the wavy shape to show a batch.

The predefined process symbol is a rectangle with an extra vertical line down each side. It points to a named sub-routine defined in its own flowchart, so you can write "Run credit check" once and reference it anywhere instead of redrawing the steps. Two more shapes round out this group:

1. Manual input uses a rectangle with a slanted top edge to show data a person types in by hand, like a passcode at a keypad.
2. Delay is a half-rounded rectangle (a D-shape) that marks a wait, such as a 24-hour hold before a step continues.

Advanced and data flowchart symbols

Data-heavy diagrams need shapes that distinguish where information rests and how it displays. These symbols show up most in system flowcharts and technical documentation.

The database symbol is a cylinder, the same icon most tools use for a stored table, and it means data written to or read from a structured database. When storage is generic rather than a formal database, the stored data symbol, an open-sided rectangle, does the same job without implying a specific technology. For sequential storage like a tape or log, some standards add a distinct shape, though the cylinder covers most modern cases.

Output that a person sees on a screen uses the display symbol, a rectangle with a curved base that looks a little like a monitor. It separates on-screen results from the printed report a document symbol implies. Finally, the merge symbol, an upside-down triangle, combines several incoming flowlines into one, the mirror of a decision that splits paths apart. Reserve these data shapes for diagrams where the storage layer actually matters, since a plain rectangle reads more clearly in a simple workflow.

Rules for using flowchart symbols correctly

Consistent shapes only help if you apply them consistently. A few rules keep your diagrams readable and standard.

• Start and end every flowchart with a terminator. A chart that just stops leaves readers unsure whether the process is complete.
• Give each decision diamond exactly one question and label every exit arrow. An unlabeled branch forces the reader to guess.
• Keep one action per process rectangle. Splitting compound steps makes the flow easier to follow and easier to change later.
• Point flowlines in a single dominant direction and avoid crossings. Crossed arrows are the fastest way to make a diagram unreadable.
• Do not invent shapes. If a standard symbol fits, use it, so anyone who knows the notation can read your chart without a key.

Follow these and your flowchart communicates on its own. Break them and even a correct diagram becomes a puzzle. The point of standard flowchart symbols is that a reader should never need a legend to understand basic flow.

Flowchart symbols in your documentation

Knowing the symbols is step one. The next step is getting flowcharts into the docs your team actually reads, and keeping them current. A screenshot of a flowchart goes stale the moment a step changes, because nobody wants to reopen a drawing tool to move one box. Text-based flowcharts solve this, since the diagram lives as code in the same file as the prose.

That is where a text renderer like Mermaid earns its place. You write the flowchart symbols as syntax (the same nine-line block above), commit it with your docs, and the diagram rebuilds on every change. Our Mermaid diagram syntax guide covers the full shape reference for flowcharts and other diagram types. Docsio generates a docs site from your product URL and renders Mermaid flowcharts live on the page, so the diagrams stay in sync with the documentation instead of drifting out of date in a folder of exported images.

For teams documenting real processes, this closes the loop: you map the workflow with standard symbols, write it as text, and publish it where readers find it. The flowchart becomes part of the docs rather than an attachment nobody updates.

FAQ

What are the 4 main flowchart symbols?

The four main flowchart symbols are the oval terminator (start and end), the rectangle process (an action step), the diamond decision (a branching question), and the arrow flowline (direction and order). Add the parallelogram for input and output, and these five shapes cover the vast majority of everyday flowcharts.

What does a diamond mean in a flowchart?

A diamond is the decision symbol. It poses a question with a branching answer, usually yes or no, and each answer leaves the diamond as a separate labeled arrow. It is the only common flowchart shape with more than one exit path, which is what lets a process split into different routes based on a condition.

What is the oval symbol in a flowchart?

The oval, also called the terminator or terminal symbol, marks where a process starts and ends. Every complete flowchart opens with a "Start" oval and closes with an "End" oval. It is sometimes drawn as a rounded pill or stadium shape, but its meaning stays the same: it defines the boundary of the flow.

Put your flowcharts where people read them

Start by memorizing the five basic shapes: terminator, process, decision, input/output, and flowline. With those, you can read or sketch almost any process diagram, and the intermediate and data symbols slot in as your diagrams grow.

When you are ready to publish those flowcharts, Docsio generates a docs site from your URL and renders Mermaid flowcharts live, so the diagrams stay current with your documentation instead of aging inside a screenshot. Map the process once, write it as text, and let the docs keep it fresh.