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Critical Path (CPM/PERT) Calculator illustration

Critical Path (CPM/PERT) Calculator

Runs the classic Critical Path Method on a plain-text task list: forward and backward passes give every task its earliest/latest start and finish, its slack, and the critical path — the chain of tasks where any delay delays the whole project. Tasks with slack can slip without hurting the deadline; critical tasks cannot. Switch to PERT mode to enter three-point estimates (optimistic-likely-pessimistic like "2-4-8"): the tool computes expected durations, the variance along the critical path, and the probability of finishing within a target duration under the standard normal approximation.

Read the full guide to this tool

Dependencies are IDs separated by semicolons, e.g. "F, Integration, 4, C; D". Leave the last field empty for tasks with no dependencies. In PERT mode the duration becomes "optimistic-likely-pessimistic", e.g. "2-4-8".
PERT only: the tool reports the probability of finishing within this duration.

Notes

  • The critical path is where management attention belongs: compressing a task with slack buys you nothing, while every day saved on a critical task moves the whole project — until a parallel path becomes critical instead.
  • Slack (float) is the honest answer to "can this wait?": a task with 3 days of slack can start 3 days late without moving the deadline; a critical task has zero.
  • PERT expected duration is (optimistic + 4×likely + pessimistic) / 6, and the finish-probability uses a normal approximation with the variances summed along the critical path — a decent approximation when the path has several independent tasks, optimistic when paths are nearly tied.
  • Cycles in the dependencies are detected and reported, not silently ignored.

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