PERT chart
Definition
A PERT (Program Evaluation and Review Technique) chart is a network diagram that maps project tasks as nodes connected by arrows showing dependencies, used to analyze task sequences and estimate project duration under uncertainty.
PERT was developed by the US Navy in the late 1950s for the Polaris missile program — a project so complex that traditional scheduling methods couldn't handle the uncertainty. The technique uses three time estimates for each task: optimistic, most likely, and pessimistic. These get combined into a weighted average (the 'expected time') to produce a probabilistic schedule.
Where a Gantt chart shows duration on a calendar axis, a PERT chart shows the dependency network: which tasks must finish before others can start. Each node represents a task or milestone; each arrow represents a dependency. The chart makes it easy to find the critical path — the longest sequence of dependent tasks that determines the minimum project duration.
PERT charts get drawn on whiteboards during planning sessions for complex, multi-team projects where timeline uncertainty is high. BoardSnap AI reads the network of nodes and arrows to produce a dependency summary, which is a useful first step before moving the plan into project management software.
Examples
- Software release: Design → Development → Unit tests → Integration → UAT → Deploy, with parallel QA and documentation tracks
- Event planning network: Venue booking, Catering, AV setup, and Invitations as parallel branches converging at 'Event ready'
- Construction network: Foundation and Permits as parallel starts, converging into Framing, then splitting into Electrical and Plumbing
- Product launch: Market research → Positioning → Content → Campaign → Launch, with Legal review as a parallel dependency on Content
Related terms
Snap a pert chart. Ship its actions.
BoardSnap turns any whiteboard — including this one — into a summary and action plan.