DFD Level 1 Diagram Examples
A DFD level 1 diagram breaks down a high-level system context into its major sub-processes, showing how data moves between them, external entities, and data stores. These diagrams are essential for systems analysts, business analysts, and software engineers to visualize process decomposition and data flow.
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About these examples.
On this page, you’ll find real-world DFD level 1 examples for common business domains: banking transaction processing, hospital appointment scheduling, university library operations, and an online bookstore. Use them as templates or inspiration for your own diagram.
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Make one yourself.
Define the main processes
Identify the key sub-processes from your level 0 diagram (e.g., 2.0 Process Order, 3.0 Manage Inventory) and label each with a verb-noun phrase inside a rounded rectangle.
Add external entities
Place the external entities (customers, suppliers, banks) that interact with the system around the boundary, using rectangles.
Include data stores
Draw the data stores (databases, files) that each process reads from or writes to, represented as open-ended rectangles or cylinders labeled with the data they hold.
Connect with data flows
Draw arrows between entities, processes, and data stores to show the direction and content of each data flow. Label each arrow with the data being transferred.
Review and balance
Ensure all inputs and outputs of the level 0 are represented, and that no data flows cross directly between external entities or data stores without a process.
Frequently asked questions
What is a DFD level 1 diagram?
How is DFD level 1 different from level 0?
What symbols are used in a DFD level 1 diagram?
Can I create a DFD level 1 diagram online?
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