Flowchart basics
Decisions, branches and loops in a flowchart
A decision is a diamond containing a question, with one labelled arrow per possible answer. Every branch must lead to a step or an end, and every loop needs an exit condition, such as a maximum number of attempts or a timeout.
Phrase the decision as a question
Write a question that can be answered without interpretation: "Is the invoice above €5,000?" rather than "Amount check". Avoid compound questions such as "Is the client new and the amount high?": split them into two successive diamonds, otherwise one combination will be forgotten.
Label every branch
Each arrow leaving a diamond carries its answer: "Yes" and "No", or "Approved", "Rejected" and "More information needed". An unlabelled arrow forces the reader to guess, and readers guess differently.
More than two answers
A diamond can have three or more outgoing arrows if the answers are mutually exclusive and together cover every case. "Which plan?" can lead to "Free", "Monthly" and "Yearly". If you cannot guarantee that every case is covered, add an explicit "Other" branch.
Loops
A loop sends the flow back to an earlier step: an incomplete application goes back to the customer, a failed payment asks for another card. Draw the return arrow clearly, preferably on the side of the chart, and label it.
Every loop needs a way out. Ask yourself what happens on the third failed payment, or if the customer never replies. The usual exits are:
- a maximum number of attempts ("After 3 failures, cancel the order"),
- a timeout shown with a delay step ("No reply within 7 days"),
- an escalation to someone else.
Decisions owned by someone
In a swimlane chart, a decision sits in the lane of whoever makes it. If nobody can say who decides, you have found a real organisational problem, not a drawing problem. Process improvement often starts there.
Checking decisions
- Does each diamond have at least two labelled exits?
- Do the answers cover every case?
- Does every branch end at a step or an end?
- Does every loop have an exit?
These checks are part of the review of common flowchart mistakes and apply equally when you check an AI-generated flowchart. In programming, the same rules map to if/else and while statements: see algorithm flowcharts.