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Critical Path Method (CPM) Example: Find the Real Finish Date in 10 Minutes

Critical Path Method (CPM) Example: Find the Real Finish Date in 10 Minutes

Critical Path Example (CPM): Find the True Finish Date in 10 Minutes

If your project schedule keeps slipping, the problem is usually not “effort”—it’s dependencies. A simple Critical Path Method (CPM) pass helps you see which tasks actually control the finish date.

Below is a practical critical path example you can copy into your next plan—plus a free kit to build a clean Gantt and CPM worksheet in minutes.

Free download: Gantt + Critical Path Quickstart Kit (PDF + Excel)
Includes a ready-to-use Gantt layout and a critical path worksheet you can reuse for every project.

What “critical path” actually means (plain English)

The critical path is the longest chain of dependent work from start to finish. Tasks on this path have zero float (no schedule slack). If any of them slip, the whole project finish date moves.

Critical Path
The dependency chain that controls the end date.
Float (Slack)
How much a task can slip without changing the finish date.
Dependencies
The logic that forces tasks to happen in a specific order.

A simple critical path example (6 tasks)

Here’s a small project with durations and dependencies. Copy this structure for any workstream (software, operations, launches, Kaizen, etc.).

Task Duration (days) Depends on Notes
A — Define scope 2 Start task
B — Requirements 4 A Needs scope baseline
C — Design 3 B Based on requirements
D — Build 6 C Execution work
E — Test 3 D Quality gate
F — Launch 1 E Release / deploy

Step-by-step: how to find the critical path

1) Forward pass (earliest dates)
Start at the beginning and calculate the earliest start/finish for each task based on its dependencies. The last task’s earliest finish is your earliest possible project finish.
2) Backward pass (latest dates)
Work backward from the finish and calculate the latest start/finish dates that do not delay the project end.
3) Float & critical path
Float = Latest Start − Earliest Start (or Latest Finish − Earliest Finish). Tasks with 0 float are on the critical path.
Result for the example above

Because the work is a straight dependency chain (A → B → C → D → E → F), the critical path is the entire chain. Total duration = 2 + 4 + 3 + 6 + 3 + 1 = 19 days. In real projects you’ll typically have parallel branches—CPM tells you which branch is the one that truly controls the finish.

5 common critical path mistakes (and how to avoid them)

  • Missing dependencies: If a task “must follow” another task, model it. Don’t rely on memory.
  • Overly large tasks: Break anything longer than 5–10 working days into smaller parts.
  • Ignoring calendars: Holidays, resource availability, and review windows change the real finish date.
  • Confusing effort with duration: Duration is calendar time; effort is work time. They aren’t the same.
  • Never updating the plan: CPM is not “set-and-forget.” Update weekly so the true critical path stays visible.
Want a clean, reusable CPM worksheet + a ready Gantt layout?
Use the same structure across every project: define tasks, map dependencies, then let the worksheet reveal the critical path.
SBDC supported PMXBOARD

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