Flowchart Symbols Explained: What Each Shape Means

Why standard symbols matter

A flowchart is only useful if the reader understands it quickly. Standard shapes let people read a diagram they have never seen before, because a diamond always means a question and a rectangle always means an action. The conventions come from process-documentation standards that have been used for decades, and they are still the safest choice for charts that will be shared.

You do not need all of the symbols. Most everyday flowcharts use five or six. The rest exist for specific industries and for more detailed technical diagrams.

The core symbols

These are the shapes you will use in nearly every chart.

Terminator (start / end)

A rounded rectangle, sometimes called a stadium or pill shape, marks where the process starts and where it finishes. Every flowchart should have exactly one start and at least one end. Label them with words such as "Start", "End", "Refund issued" or "Request closed".

Process

A plain rectangle is an action or operation: "Verify email address", "Pack the order", "Calculate total". Each process shape should have one arrow in and one arrow out. If a step has two arrows out, it is really a decision and should use a diamond.

Decision

A diamond asks a question and splits the flow. Put the question inside the diamond and label every exit with the answer. Yes/no questions are easiest to read, but a decision can have three or more exits, such as "Low", "Medium" and "High" priority.

Input / output

A parallelogram shows data entering or leaving the process: "Customer enters shipping address", "System sends invoice". It separates information handling from ordinary actions, which is especially useful in software and data-flow charts.

Data store and document

A cylinder represents stored data such as a database or spreadsheet. A shape with a wavy bottom edge represents a document, report or printed record. Use them to show where information is saved or produced, so readers know which steps read from or write to which place.

Connectors and arrows

Arrows give the direction of flow. Keep them straight where possible and make sure every arrowhead points to the next step. A small circle, called an on-page connector, lets a path jump to another part of the chart without a long line crossing everything. An off-page connector, drawn as a pentagon, points to a continuation on another sheet.

Less common symbols

• Predefined process (rectangle with double side lines): a step that is described in detail in another chart.
• Preparation (hexagon): setup work before the main flow, common in programming charts.
• Manual input and manual operation: steps done by hand rather than automatically.
• Delay (D-shaped): a wait before the next step.
• Annotation (open bracket): a note attached to a step without being part of the flow.

Rules of thumb

• One idea per shape. A box saying "Check stock and email the customer" should be two boxes.
• Keep the flow in one direction, usually top to bottom or left to right.
• Label every branch leaving a decision.
• Use colour to group or highlight, but never as the only way to tell shapes apart.
• Be consistent. If a diamond is a decision in one place, it is a decision everywhere.

Using the symbols in FlowchartLab

The Flowchart Maker toolbar includes Start/End, Process, Decision, Input/Output, Data Store and Document shapes, so the standard set is one click away. Add a shape, type its label, drag arrows between shapes, and export when you are done. The guide on how to make a flowchart walks through the whole process from first idea to finished diagram.