PERT Chart

What is a PERT Chart?

A PERT (Program Evaluation and Review Technique) chart is a project management tool that maps out task dependencies, timelines, and critical paths using a network diagram of connected nodes representing project activities.

Think of it like a GPS for your project that shows not just the destination but every possible route, traffic jam, and shortcut along the way.

Unlike simple Gantt charts that show when tasks happen, PERT charts reveal why certain tasks must happen in specific sequences and which delays will derail your entire project.

PERT charts excel at managing uncertainty by using three time estimates (optimistic, pessimistic, and most likely) for each task, calculating the probability of meeting deadlines.

Developed by the U.S. Navy in the 1950s for the Polaris missile program, this technique helped them finish two years ahead of schedule, and it's been saving projects ever since.

PERT Charts in Modern Project Management

PERT charts transform chaotic project landscapes into navigable roadmaps. They're especially powerful for complex initiatives with multiple interdependencies, uncertain durations, and high stakes for on-time delivery.

Software Development Applications

Agile teams combine PERT analysis with sprint planning to manage dependencies across teams. Spotify uses modified PERT charts to coordinate feature releases across 100+ autonomous squads. By visualizing dependencies, they reduced inter-team conflicts by 45% and improved release predictability.

Construction and Engineering

The new Apple Park campus used PERT charts to coordinate 13,000 construction workers. Every glass panel, steel beam, and system installation was mapped, with critical paths updated daily. This precision helped them complete the $5 billion project within 6 months of the original estimate.

Product Launch Coordination

Samsung's Galaxy phone launches involve thousands of tasks across R&D, manufacturing, marketing, and distribution. PERT charts help them identify which delays in component sourcing will impact launch dates versus which have slack time built in.

Research and Development

Pharmaceutical companies use PERT charts for drug development pipelines where each phase has uncertain durations. Pfizer's COVID vaccine development used advanced PERT analysis to run normally sequential phases in parallel wherever possible, cutting years from the timeline.

Essential PERT Chart Components

Node Elements

• Task identifier and descriptive name

• Duration estimates (optimistic, likely, pessimistic)

• Early start and early finish dates

• Late start and late finish dates

Relationship Types

• Finish-to-Start (most common): Task B starts when Task A finishes

• Start-to-Start: Tasks begin simultaneously

• Finish-to-Finish: Tasks must complete together

• Start-to-Finish (rare): Task B finishes when Task A starts

Critical Path Indicators

• Zero slack activities highlighted in red

• Total project duration calculation

• Parallel path identification and analysis

• Near-critical paths within 10% of critical

Time Calculations

• Forward pass: Calculate earliest possible start times

• Backward pass: Determine latest allowable start times

• Slack calculation: Difference between early and late starts

• PERT weighted average for task durations