How to Calculate the Critical Path

The critical path tells you your shortest possible finish date and which tasks you cannot afford to slip.

For the full concept, see Critical Path Method.

Steps

1. List all activities and estimate each one’s duration.
2. Map dependencies — which activities must precede which.
3. Run a forward pass to get Early Start and Early Finish for each activity.
4. Run a backward pass to get Late Start and Late Finish.
5. Calculate float (LS − ES); activities with zero float form the critical path.
6. Check for multiple critical paths, which make the schedule more fragile.

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