Reading a flowchart means following a path from a starting point through a series of shapes, each representing a different type of action or decision, until you reach an endpoint. Every shape has a specific meaning, and arrows tell you which direction to move. Once you learn the handful of core symbols, you can read virtually any flowchart you encounter.
The Four Shapes You Need to Know
Flowcharts are built from a small set of standardized symbols defined by ISO 5807, an international standard that has been in place since 1985 and remains current today. You only need to recognize four shapes to read most flowcharts:
- Oval (or rounded rectangle): Marks the start or end of the process. You’ll usually see the word “Start” or “End” inside it. Every flowchart has at least two of these, one to begin and one to finish.
- Rectangle: Represents a step, action, or task. This is the most common shape. It might say something like “Review application” or “Calculate total.”
- Diamond: Represents a decision point. It contains a question, and two or more arrows lead out of it, each labeled with a possible answer (typically “Yes” and “No”).
- Parallelogram: Represents data going in or coming out. If the process requires information to be entered or a result to be displayed, this shape appears.
Beyond these four, you may occasionally see a shape that looks like a page with a wavy bottom edge (representing a document or report), a cylinder (representing a database), or a rectangle with a sloped top edge (representing manual input from a user). These are less common but follow the same logic: the shape tells you what type of activity is happening, and the text inside tells you the specifics.
Following the Arrows
Arrows are the connective tissue of a flowchart. They show you the order of operations, pointing from one shape to the next. The standard convention is to read top to bottom and left to right, just like reading a page of text. When a flowchart is well constructed, you should never wonder which direction to go because every connection has an arrow indicating the path.
Start at the oval labeled “Start” and follow the arrow to the first shape. Complete whatever that shape describes, then follow the next arrow. Continue this process until you reach the oval labeled “End.” If you hit a diamond (decision point), read the question inside, pick the answer that applies, and follow the arrow labeled with that answer. The other paths are for other scenarios.
How Decision Points Work
Diamonds are where flowcharts get interesting. Instead of a single path forward, the process branches. The question inside the diamond is almost always phrased to have a clear “Yes” or “No” answer, though some flowcharts use “True/False” or other short labels.
Each outgoing arrow from a diamond should be labeled so you know which path corresponds to which answer. If you’re reading a flowchart that asks “Is the order over $50?” and your answer is yes, you follow the arrow marked “Yes.” The “No” arrow leads to a different sequence of steps. These branches may eventually merge back into a single path, or they may lead to entirely different endpoints.
Some decisions have more than two outcomes. A diamond might ask “What is the customer’s membership level?” with three arrows leading to “Gold,” “Silver,” and “Standard.” The principle is the same: read the question, pick your answer, follow that arrow.
Recognizing Loops
Not every flowchart moves in a straight line from top to bottom. Sometimes an arrow leads backward, pointing to a shape you’ve already passed. This creates a loop, meaning the process repeats a set of steps until a condition changes.
A common example: a decision diamond asks “Is the form complete?” If the answer is “No,” the arrow loops back to an earlier step like “Fill in missing fields.” You cycle through those steps again until you can answer “Yes,” at which point the flowchart moves forward. When you see an arrow pointing upward or backward, you’re looking at a loop. Follow it just as you would any other arrow, returning to the earlier step and working through the sequence again.
Swimlane Flowcharts
Some flowcharts divide the page into horizontal or vertical bands called swimlanes. Each lane is labeled with a person, department, or role. A lane labeled “Customer” contains all the steps the customer performs, while a lane labeled “Shipping” contains everything the shipping team handles. Arrows cross between lanes to show handoffs.
Reading a swimlane flowchart works the same way as reading a basic one. You still follow arrows from shape to shape, start to end. The lanes just add one extra piece of information: who is responsible for each step. When an arrow crosses from the “Sales” lane into the “Accounting” lane, that tells you the task is being handed from one team to another. Pay attention to which lane a shape sits in, and you’ll understand not just what happens but who makes it happen.
Tips for Complex Flowcharts
Simple flowcharts with five or ten steps are easy to trace. Larger ones, especially those documenting business processes or software systems, can fill an entire wall. A few strategies help.
First, locate every oval. These are your anchors. Identify where the process starts and where it can end. Some flowcharts have multiple endpoints representing different outcomes (approved vs. rejected, for instance). Knowing the possible destinations helps you understand the big picture before you trace individual paths.
Second, identify the decision diamonds. These are the points where the process branches, and they reveal the logic driving the entire chart. Reading just the questions inside the diamonds often gives you a high-level summary of what the flowchart is evaluating.
Third, trace one complete path at a time. Pick the most straightforward route from start to end, following a single set of answers through each decision. Once you understand that path, go back and explore the branches. Trying to absorb every path simultaneously in a large flowchart leads to confusion.
Finally, look for small circles or pentagons containing a letter or number. These are connectors, used when a flowchart is too large to fit on one page or when drawing a long arrow would create visual clutter. A connector labeled “A” on one part of the chart links to another connector labeled “A” elsewhere. Jump from one to the other as if a single arrow connected them.
Flowcharts vs. Specialized Diagrams
In workplace settings, you may encounter diagrams that look like flowcharts but use unfamiliar symbols. The most common alternative is BPMN, or Business Process Model and Notation. BPMN uses circles instead of ovals for start and end events, rounded rectangles for tasks, and a larger set of specialized icons to represent things like timers, messages, and parallel tasks.
BPMN is more complex and more standardized than a traditional flowchart. It follows a globally recognized format that allows diagrams to be shared across different software platforms. If you’re comfortable reading a basic flowchart, you already understand the core logic of BPMN. The difference is mainly in the number and specificity of symbols. Traditional flowcharts are designed to be intuitive for a general audience, while BPMN assumes a more technical reader and packs more information into each diagram.
If you encounter a diagram with symbols you don’t recognize, check whether it includes a legend or key. Most well-made diagrams define any non-standard symbols somewhere on the page.