Flowchart Symbols & Notation
Master the standard flowchart symbols, their meanings, and how to use them correctly. Learn the visual vocabulary that makes flowcharts universally understood.
Flowcharts use a standardized set of symbols that make them universally understood, regardless of language or industry. In this lesson, we'll learn each symbol, its meaning, and see practical examples of how to use them.
The Essential Symbol Set
While there are dozens of flowchart symbols, you only need to master a core set to create effective flowcharts for most situations.
Terminal Symbols (Start/End)
Terminal symbols mark the beginning and end of a process.
Symbol | Shape | Usage |
|---|---|---|
([Start]) | Rounded rectangle / Pill | Marks the beginning of a process |
([End]) | Rounded rectangle / Pill | Marks the end of a process |
[!NOTE] Best Practice Every flowchart should have exactly one Start symbol. It may have one or more End symbols (for different exit paths).
Process Symbols (Action/Operation)
Process symbols represent an action, operation, or step in the workflow.
Symbol | Shape | Usage |
|---|---|---|
[Action] | Rectangle | A single step or operation |
Decision Symbols
Decision symbols represent a point where the process branches based on a condition.
Symbol | Shape | Usage |
|---|---|---|
{Condition?} | Diamond | A yes/no or multi-way decision |
[!TIP] Label Your Branches Always label the outgoing arrows from decision symbols. Use clear labels like "Yes/No", "Pass/Fail", or specific values.
Input/Output Symbols
Input/Output symbols represent data entering or leaving the process.
Symbol | Shape | Usage |
|---|---|---|
[/Input/] | Parallelogram | Data input to the process |
[/Output/] | Parallelogram | Data output from the process |
Document Symbols
Document symbols represent documents or reports generated by the process.
Symbol | Shape | Usage |
|---|---|---|
[[Document]] | Rectangle with wavy bottom | A document or report |
Database Symbols
Database symbols represent data storage or retrieval.
Symbol | Shape | Usage |
|---|---|---|
[[(Database)]] | Cylinder | Database or data storage |
Connector Symbols
Connectors show the flow direction and link different parts of the flowchart.
Flow Lines (Arrows)
Arrows show the direction of process flow.
Off-Page Connectors
When a flowchart spans multiple pages, off-page connectors link them.
On-Page Connectors
For complex flowcharts, on-page connectors avoid crossing lines.
Complete Symbol Reference Table
Symbol | Mermaid Syntax | Shape | Name | When to Use |
|---|---|---|---|---|
([Text]) | ([Text]) | Rounded | Terminal | Start or end of process |
[Text] | [Text] | Rectangle | Process | Action or operation |
{Text} | {Text} | Diamond | Decision | Branch point |
[/Text/] | [/Text/] | Parallelogram | I/O | Input or output data |
[[Text]] | [[Text]] | Wavy rect | Document | Report or document |
[[(Text)]] | [[(Text)]] | Cylinder | Database | Data storage |
((Text)) | ((Text)) | Circle | Connector | Link to another point |
==Text== | ==Text== | Double line | Predefined process | Sub-process call |
Practical Examples
Example 1: User Registration Flow
Example 2: Bug Report Triage
Example 3: E-Commerce Checkout
Symbol Usage Guidelines
Do's and Don'ts
Do | Don't |
|---|---|
Use consistent symbol shapes | Mix shapes for the same purpose |
Label decision branches clearly | Leave branches unlabeled |
Keep text concise inside symbols | Write paragraphs inside symbols |
Use standard symbols | Invent custom symbols without a legend |
Flow top-to-bottom or left-to-right | Create confusing flow directions |
Use color purposefully | Use random colors without meaning |
[!WARNING] Common Mistake Don't use a rectangle for decisions just because it's easier to type. The diamond shape is universally recognized as a decision point: using the wrong shape confuses readers.
Color Coding Conventions
While not standardized, these color conventions are widely used:
Color | Typical Meaning |
|---|---|
Green | Start, success, positive outcome |
Red | End, error, failure, stop |
Orange/Yellow | Decision points, warnings |
Blue | Process steps, actions |
Purple | Data storage, databases |
Yellow | Documents, reports |
Practice Exercises
Exercise 1: Symbol Identification
For each description, identify the correct symbol shape:
- The point where a user's subscription status is checked
- The step where a report is generated
- The beginning of the order fulfillment process
- Data being read from a configuration file
- Saving a record to the database
- A reference to a sub-process defined elsewhere
Click to see answers
- Diamond
{}: Decision point - Wavy rectangle
[[]]: Document - Rounded rectangle
([ ]): Terminal (Start) - Parallelogram
[/ /]: Input - Cylinder
[[( )]]: Database - Circle
(( )): Connector (or double-lined rectangle for predefined process)
Exercise 2: Fix the Flowchart
This flowchart has symbol errors. Identify and fix them:
[Start] → [Check user role] → [Admin?] → [Show admin panel] → [End]
Click to see the corrected version
([Start]) → [Check user role] → {Admin?} →|Yes| [Show admin panel] → ([End])
→|No| [Show user panel] → ([End])
Errors fixed:
- Start should be
([Start])(terminal, not process) - "Admin?" should be
{Admin?}(decision, not process) - End should be
([End])(terminal, not process) - Missing the "No" branch from the decision
- Branches should be labeled
Exercise 3: Draw a Flowchart
Create a flowchart for "Making a phone call" using at least:
- 2 terminal symbols
- 4 process symbols
- 2 decision symbols
- 1 input/output symbol
- Proper flow arrows with labels
Key Takeaways
- Flowcharts use standardized symbols that are universally understood
- The core symbol set includes: terminals, processes, decisions, I/O, documents, databases, and connectors
- Always label decision branches clearly
- Use consistent shapes: don't mix symbols for the same purpose
- Color coding can enhance readability but isn't required
- Keep symbol text concise: use descriptions outside the diagram if needed
- In the next lesson, we'll apply these symbols to build your first flowcharts step by step
[!SUCCESS] You've Completed Lesson 4 You now know the standard flowchart symbols and how to use them. In the next lesson, we'll put this knowledge into practice by building flowcharts from scratch with step-by-step examples.