What happens with a dependency cycle?

The calculator detects it and reports an error directly, since a cycle among phases has no valid schedule at all.

Can a phase have zero duration, like a review gate?

Yes, a zero-duration phase is treated as an instantaneous checkpoint, still respecting its dependencies and still able to sit on the critical path if the timing works out that way.

Phase Dependency Planner

Give each phase a duration and the phases it depends on. This finds the project finish date and highlights the critical path, the specific phases with zero slack that would delay the finish date if any one of them slipped.

Comparing running work in parallel vs one after another, without full dependency modeling? See Parallel vs Sequential Work Comparator.

Want to learn more?

Critical Path Basics: Why Some Delays Slip the Deadline

Worked example

Research, at 4 days, and Design, at 2 days, both start at kickoff, and Build, at 5 days, depends on both of them finishing first. The project finishes 9 calendar days after kickoff, driven by the 4-day Research phase feeding directly into the 5-day Build phase, while Design has 2 days of slack in this schedule and sits off the critical path entirely. Shorten Research from 4 days down to 2 instead, and the finish date pulls in by 2 full days, since Research now shares the critical path with Design.

Common mistakes

Assuming shortening any phase speeds up the finish date. Only phases on the critical path, the ones with zero slack, actually move it when shortened.
Forgetting to list every real dependency for a phase. A missing dependency lets the planner schedule that phase earlier than it should actually be able to start.

Limitations

Durations are fixed numbers entered directly, with no uncertainty modeled anywhere in the calculation. This is a deterministic planning model, not a probabilistic estimate that accounts for risk or variance.

Frequently asked questions

What happens with a dependency cycle?: The calculator detects it and reports an error directly, since a cycle among phases has no valid schedule at all.
Can a phase have zero duration, like a review gate?: Yes, a zero-duration phase is treated as an instantaneous checkpoint, still respecting its dependencies and still able to sit on the critical path if the timing works out that way.