ANSI Standard Flowchart Symbols: What Each Shape Means

Published November 10, 2026 · Updated November 10, 2026 · 7 min read · by the Sakura5 team

The ANSI standard flowchart symbols are a small set of shapes defined in ANSI X3.5-1970: an oval-style terminal for start and end, a rectangle for a process, a diamond for a decision, a parallelogram for input and output, a circle for a connector, and arrows for the flow of control. Almost every flowchart symbol chart you’ll find online descends from that standard, and the international version, ISO 5807, keeps the same core shapes.

Here’s the part most guides skip: “ANSI” is the name of the standards body, not a modern rulebook you have to pass an audit against. The original standard dates from the era of punched cards and magnetic tape, which is why the full list still includes shapes nobody draws today. For homework, documentation and process charts, what matters is using the common shapes the way the standard meant them.

This guide covers where the ANSI symbols came from, the core shapes and their meanings, the older shapes worth recognizing, a worked example you can copy for a coursework flowchart, and answers to the questions people ask most about ANSI versus ISO.

Where the ANSI standard flowchart symbols come from

ANSI X3.5-1970, titled “Flowchart Symbols and Their Usage in Information Processing,” was written for people documenting computer programs and data-processing systems. It defined each symbol by what it represented in a machine: a step of processing, a branch, a read from a card, a write to tape. The shapes were chosen so that a flowchart could be read without knowing which programming language was behind it.

The international standard that followed, ISO 5807:1985, covers data, program and system flowcharts and keeps the same vocabulary for the core shapes. If a course or a company asks for “ANSI symbols,” they almost always mean this shared set. If you need to cite a standard formally, check which edition your instructor or employer actually uses, because the document you’ll be asked for may be the ISO one.

The other thing to know is that the standard governs shapes and conventions, not layout taste. It tells you a diamond means a decision; it doesn’t tell you how wide to make your boxes. That’s why two correct ANSI flowcharts can look quite different.

The core ANSI standard flowchart symbols and what they mean

These six cover nearly every chart you’ll be asked to draw. Each shape answers one question about the step inside it.

1. Terminal: where does it start and stop?

The terminal is drawn as a rounded oval or pill shape. It marks the single entry point and each exit point of the chart. Label it with “Start” and “End,” or with a named event such as “Order received.”

2. Process: what gets done?

The process symbol is a plain rectangle. It holds one operation or a group of operations that change data or move the flow forward, such as “Calculate average” or “Add 1 to counter.” One arrow in, one arrow out.

3. Decision: which way next?

The decision symbol is a diamond with one entry and two or more labeled exits. In practice, use two: “Yes” and “No,” or “True” and “False.” Write the question so it can be answered with no ambiguity, for example “Average at least 60?”

4. Input/output: what comes in or goes out?

The input/output symbol is a parallelogram. It marks data being read or results being produced, without saying which device does it. “Read three quiz scores” and “Display result” both belong here.

5. Connector: where does this continue?

A small circle with a letter or number links two points on the same page, so you don’t have to draw an arrow across the whole chart. A matching circle with the same label marks where the flow resumes. The off-page connector, drawn as a pentagon, does the same across pages.

6. Flow line: in what order?

Flow lines connect symbols and show direction with arrowheads. The standard convention is top to bottom and left to right; arrowheads are required whenever the flow runs against that default, and they’re a good habit everywhere.

Older ANSI symbols you may still meet

The rest of the set describes hardware and documents. You’ll see these in textbooks, legacy documentation and the occasional exam, so it helps to know what they stand for, even if you never draw them.

• Predefined process — a rectangle with double vertical bars. A sub-routine or procedure defined elsewhere.
• Preparation — a hexagon. A setup step such as initializing a variable or a loop counter.
• Document — a rectangle with a wavy bottom edge. Information on paper, such as a report or a form.
• Manual input — a rectangle with a sloped top. Data keyed in by a person.
• Manual operation — an upside-down trapezoid. A step done by hand with no machine involved.
• Stored data and delay — a rounded-side shape for stored data, and a half-oval for a wait.
• Punched card and magnetic tape — period storage media, now mostly historical.

The American Society for Quality publishes a clear reference on flowchart symbols and when to use them if you want a second source on the common shapes. For a gentler walk-through of the first six, see our flowchart symbols and meanings for beginners.

A worked example: a pass/fail grader in ANSI symbols

Say Priya is in an intro programming class, and the lab asks for a flowchart of a program that reads three quiz scores out of 100, averages them, and reports pass if the average is 60 or higher. Here is the chart, symbol by symbol.

1. Terminal: “Start.”
2. Input/output: “Read score 1, score 2, score 3.”
3. Process: “Average = (score 1 + score 2 + score 3) / 3.”
4. Decision: “Average at least 60?”
5. Input/output (Yes branch): “Display Pass.”
6. Input/output (No branch): “Display Fail.”
7. Terminal: “End,” with both branches arriving at the same terminal.

Test it with real numbers before you hand it in. With scores of 52, 71 and 64, the sum is 187 and the average is about 62.3, so the flow takes the Yes branch and displays Pass. With 40, 55 and 61, the sum is 156, the average is 52, and the flow takes the No branch. If you can trace both paths by finger without hitting a dead end, the chart is correct. Two common slips: sending only the Yes branch to the End terminal, and leaving the decision with a single unlabeled exit.

To get to that chart faster, start from the steps rather than the shapes. In Mindmap AI you can type or paste the assignment text, let the AI (a Pro feature) break it into a map of inputs, calculations and outcomes, and then read the outline view as your ordered step list. Each node becomes one ANSI symbol, and you do the drawing last.

Edge cases: loops, multiple exits and which standard to follow

A loop is just a decision whose “No” arrow runs back up to an earlier step. Draw the return arrow clearly, and make the exit condition obvious in the diamond’s label. If the loop counts, add a preparation hexagon or a process box that sets the counter before the loop starts.

When a decision seems to need three exits, split it into two diamonds in sequence. It reads more cleanly and matches how the standard is normally used. When a chart outgrows one page, break out a predefined process and chart that part separately, instead of cramming it with connectors.

If your team uses a modern tool with its own shape library, the shapes are almost always the same core set. Consistency within one chart matters more than strict historical purity. If your goal is to choose between flowcharts and other diagram types in the first place, our guide to flowchart vs diagram sets out when each one fits. And if you’re still collecting the steps, Mindmap AI works well as the free-form stage before you draw.

FAQ

What are the ANSI standard flowchart symbols?

The core ANSI flowchart symbols are the terminal (oval) for start and end, the process (rectangle) for an action, the decision (diamond) for a yes-or-no branch, the input/output (parallelogram) for data in or out, the connector (circle) for joining points, and flow lines with arrowheads for direction. Older shapes cover documents, cards and tape.

Is there an official ANSI flowchart standard today?

The original standard is ANSI X3.5-1970, and the international equivalent is ISO 5807:1985. Both define the same core shapes. In practice, most schools and companies simply expect the common set, so check your assignment or style guide to see which document, if any, it names.

What is the difference between ANSI and ISO flowchart symbols?

For the everyday shapes, there is no meaningful difference: terminal, process, decision, input/output and connector look and mean the same thing. The ISO standard is broader, covering system and program network charts as well. If you only draw process or program flowcharts, either label points to the same shapes.

Do I have to use the parallelogram for input and output?

For coursework and algorithm charts, yes, because the parallelogram is the standard symbol and graders often look for it. For a quick business process chart, many people use plain rectangles for everything. Use the parallelogram whenever the assignment mentions ANSI, ISO or standard flowchart symbols.

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