If you've ever opened a flowchart template and stared at a grid of unfamiliar shapes wondering what they all mean, you're not alone. Flowchart symbols are the shared visual language behind process mapping, software design, business workflows, and even simple decision-making diagrams. Knowing what each symbol means is the difference between a flowchart that actually communicates and one that just looks like a mess of shapes.

What exactly are flowchart symbols?

Flowchart symbols are standardized shapes used to represent different types of actions, decisions, inputs, outputs, and connections within a process diagram. Each shape carries a specific meaning so that anyone familiar with the conventions can read the chart without needing extra explanation.

The most widely accepted standards come from ISO 5807, which defines flowchart symbol conventions for information processing. These standards have been around since the 1980s and remain the backbone of how professionals create and interpret flowcharts today.

What do the basic flowchart symbols mean?

Most flowcharts rely on a small set of core symbols. Here's what each one represents:

Terminal (Oval or Rounded Rectangle)

This shape marks the start or end of a process. You'll see it at the beginning of your flowchart with labels like "Start" or "Begin" and at the end with "End" or "Done." It signals that the process either kicks off or wraps up here.

Process (Rectangle)

The rectangle is the workhorse of any flowchart. It represents any action, task, or operation that takes place during the process. Examples include "Send email," "Calculate total," or "Review document." If something is being done, it goes in a rectangle.

Decision (Diamond)

The diamond symbol represents a yes/no question or true/false condition. It always has at least two exit paths typically labeled "Yes" and "No" (or "True" and "False"). Decisions are what make flowcharts dynamic rather than just a linear list of steps. If you want to go deeper on how to use this shape effectively, our guide on using the decision diamond symbol in flowcharts covers common patterns and examples.

Input/Output (Parallelogram)

This slanted shape indicates that data is being entered into or displayed by the system. Think "User enters password" or "Display account balance." It's specifically about data flow, not general actions.

Arrow (Flowline)

Arrows connect the other symbols and show the direction of the process flow. Without them, the reader has no idea what order the steps happen in. Some flowcharts also use dashed arrows to represent connections to separate parts of the diagram or to indicate a different type of relationship.

Connector (Small Circle)

A small circle is used when a flowchart spans multiple pages or sections. It acts as a bridge one circle on one page connects to a matching circle on another. This keeps the chart organized when it gets too large for a single view.

Predefined Process (Rectangle with Double Vertical Lines)

This looks like a regular rectangle but has vertical bars on each side. It refers to a process that is defined elsewhere a subroutine, a separate flowchart, or a standard procedure. You don't need to spell out every step inside it because it's already documented in another place.

What about less common flowchart symbols?

Beyond the basics, there are several symbols you might encounter in specialized diagrams:

• Document symbol (rectangle with a wavy bottom edge) represents a physical or digital document produced during the process, like a report or invoice.
• Multiple documents (stacked wavy-bottom rectangles) indicates more than one document is generated.
• Manual input (rectangle with a slanted top edge) a step where a person manually enters data, usually via keyboard.
• Manual operation (trapezoid with the wider side on top) a process done by hand, not automated.
• Preparation symbol (rectangle with a slanted side edge) used to mark initialization or setup steps before the main process begins.
• Storage symbol (inverted triangle) data stored in a buffer or temporary location.
• Database symbol (cylinder shape) represents data stored in a database.
• Display symbol (rectangle with a curved bottom) output shown on a screen or monitor.
• Merge symbol (inverted triangle) combines multiple paths into one.
• Extract symbol (triangle) splits or sorts data into separate streams.

These symbols appear more often in system flowcharts and data flow diagrams than in basic process maps. For a full reference of standardized symbols, take a look at the ISO 5807 standard flowchart symbol reference.

When would you actually need to know flowchart symbols?

Flowchart symbols show up in more situations than most people expect:

• Software development mapping out algorithms, user flows, and system logic before writing code.
• Business process management documenting how a department handles tasks like onboarding, approvals, or customer service.
• Troubleshooting creating diagnostic flowcharts to help technicians or support teams identify problems step by step.
• Academic and technical writing explaining processes in research papers, textbooks, or reports.
• Project planning visualizing task sequences, dependencies, and decision points.
• Quality control standardizing workflows so everyone on a team follows the same process.

In each of these cases, using the wrong symbol or making up your own creates confusion. Standardized symbols let any team member or stakeholder read the chart the same way.

What are the most common mistakes people make with flowchart symbols?

Even experienced professionals get tripped up. Here are the errors that come up most often:

1. Using process rectangles for decisions. If a step involves a yes/no question, it needs to be a diamond, not a rectangle. Mixing them up makes the logic impossible to follow.
2. Forgetting flow direction arrows. Some people assume the layout makes the order obvious, but without arrows, readers can misinterpret the sequence especially at branches and loops.
3. Inconsistent symbol usage. Using a rounded rectangle for the start but a regular rectangle for the end (or vice versa) sends mixed signals about what's a terminal point and what's an action.
4. Overcomplicating the chart. Cramming too many decisions and branches into a single flowchart makes it unreadable. Sometimes it's better to break the process into smaller sub-charts using predefined process symbols.
5. Ignoring standard conventions. Making up symbols or repurposing shapes for meanings they don't traditionally hold means the chart only makes sense to the person who created it.
6. Missing start and end points. Every flowchart should have clear terminal symbols. A chart that begins mid-process leaves the reader guessing about context.

How do you decide which flowchart symbol to use?

Ask yourself these questions about each step in your process:

• Does something happen here? Use a rectangle (process symbol).
• Is there a question with different outcomes? Use a diamond (decision symbol).
• Is data being entered or outputted? Use a parallelogram (input/output symbol).
• Is this the very beginning or the very end? Use an oval (terminal symbol).
• Does this step refer to another documented process? Use a double-bordered rectangle (predefined process).
• Is a document created at this step? Use the wavy-bottom rectangle (document symbol).

When in doubt, stick with the basic six symbols. Most flowcharts don't need the specialized ones. Starting simple keeps your diagram clean and readable.

Do different industries use flowchart symbols differently?

The core symbols stay the same across industries, but the context changes. A software engineer might lean heavily on predefined process symbols because they reference functions or modules. A business analyst might use more document and manual input symbols because they're mapping human-driven workflows. An electrical engineer might use completely different diagram types (like circuit diagrams) that share the concept of standardized symbols but follow different standards.

For most general-purpose process flowcharts, the standard set described above works across all industries without modification.

Quick reference: flowchart symbols at a glance

Symbol Shape	Name	Meaning
Oval / Rounded rectangle	Terminal	Start or end of the process
Rectangle	Process	An action or task
Diamond	Decision	A yes/no question or condition
Parallelogram	Input/Output	Data entering or leaving the system
Arrow	Flowline	Direction of process flow
Small circle	Connector	Link between different sections or pages
Double-bordered rectangle	Predefined Process	A process defined elsewhere
Wavy-bottom rectangle	Document	A document produced in the process

Practical checklist before you publish a flowchart

1. Every flowchart starts with a terminal symbol (start) and ends with one (end).
2. All decision diamonds have labeled exit paths usually "Yes" and "No."
3. Every shape is connected by arrows showing the correct flow direction.
4. You've used consistent symbol meanings throughout the entire chart.
5. Complex processes are broken into sub-charts using predefined process symbols.
6. A teammate who didn't create the chart can read it without asking you questions.
7. You've referenced the standard symbol reference to confirm your symbols follow established conventions.

Print this list and run through it every time you finish a flowchart. It takes two minutes and catches most errors before anyone else sees the diagram.