Flowchart basics

Flowchart symbols and their meaning

Five symbols cover most flowcharts: the oval (start or end), the rectangle (an action), the diamond (a decision), the parallelogram (input or output) and the arrow (the order of steps). The others are useful in specific cases, such as documents, databases or waiting times.

By Flowchartio · Updated October 25, 2026 · 2 min read

The essential symbols

Terminator (oval or rounded rectangle): where the process starts and where it ends. Label it with the triggering event ("Order received") or the outcome ("Order shipped").
Process (rectangle): one action. Start the label with a verb: "Check stock", "Send invoice".
Decision (diamond): a question with two or more answers. Each outgoing arrow carries an answer, such as "Yes" and "No". The article on decisions and loops covers the details.
Input/Output (parallelogram): information entering or leaving the process, such as a form submitted by a customer or a report produced.
Flow line (arrow): the order of the steps. Arrows should not cross when you can avoid it.

With these five, you can draw almost any business process.

Useful additional symbols

Document (rectangle with a wavy bottom): a paper or digital document is created or used.
Predefined process (rectangle with double vertical edges): a sub-process detailed in another chart. Many tools also use it for an automated step.
Database or stored data (cylinder): information is saved or read.
Delay (D-shaped symbol): the process waits, for example "Wait 48 hours for a reply".
Manual input (slanted top): someone types data in.
On-page and off-page connectors (small circle or pentagon): the flow jumps elsewhere on the page or to another page, which avoids long crossing arrows.

Is there an official standard?

Yes. The shapes were standardised for information processing by ANSI in the 1960s and later by the international standard ISO 5807. In practice, teams rarely need the full list. What matters is consistency: the same shape always means the same thing in your diagrams, and anyone outside your team can read them.

Symbols in Flowchartio

Flowchartio keeps a deliberately short set so that every chart stays readable:

start and end (pill shape),
step (rectangle) for work done by a person,
automatic step (rectangle with side bars) for work done by a system, optionally bound to an API endpoint,
decision (diamond),
delay, for waiting times.

Each owner of the process gets its own column, as in a swimlane diagram. When you export to Mermaid code, each shape is converted to its Mermaid equivalent.

Common mistakes with symbols

Using a rectangle for a question. If the step has several possible outcomes, it is a decision.
Mixing shapes inconsistently, such as ovals for some actions and rectangles for others.
Writing a whole paragraph inside a shape. Keep labels to a short verb phrase and move explanations to notes.

To see how these symbols combine into different kinds of charts, read types of flowcharts.