PMP Exam Prep: Critical Path Method

Critical Path Method (CPM)

The critical path is the longest sequence of activities in a project that determines the shortest possible project duration. Activities on the critical path have zero float (slack).

Steps to Calculate

1. List all activities and their durations.
2. Identify dependencies.
3. Draw a network diagram.
4. Calculate early start (ES) and early finish (EF) (forward pass).
5. Calculate late start (LS) and late finish (LF) (backward pass).
6. Determine float: Float = LS - ES or LF - EF.
7. Identify the critical path (activities with zero float).

Interactive Calculator

Enter activities, durations, and dependencies to calculate the critical path.

Example

Activities: A (5 days, no predecessor), B (3 days, depends on A), C (2 days, depends on B). Critical path: A → B → C (10 days).