What is the critical path and how to calculate it?

Critical path — this is the sequence of tasks in a project that determines the minimum time to complete the entire project. Tasks on the critical path have no float (slack), and any delay in them will lead to a delay in the entire project.

How to calculate the critical path:

1. Create a list of all project tasks with their durations and dependencies.
2. Build a network diagram of the project, where nodes are tasks and edges are dependencies.
3. Calculate early start and finish times for tasks (forward pass).
4. Calculate late start and finish times for tasks (backward pass).
5. Determine the float (slack) for each task: the difference between late and early start times.
6. Tasks with zero float form the critical path.

Example:

• Task A: 3 days
• Task B (depends on A): 4 days
• Task C (depends on A): 2 days
• Task D (depends on B and C): 1 day

Critical path: A → B → D (3 + 4 + 1 = 8 days)

Task C has float because its duration is shorter and it does not affect the overall timeline.

Thus, the critical path helps understand which tasks cannot be delayed without increasing the project duration.