What is the critical path?

The critical path is the longest sequence of dependent tasks from project start to finish. Any delay to a task on this path directly delays the project end date. Tasks on the critical path have zero total float (slack).

What is total float (slack)?

Total float is how much a task can be delayed without pushing out the project end date. It equals Latest Start minus Earliest Start (or Latest Finish minus Earliest Finish). Zero float means the task is critical.

Can a project have more than one critical path?

Yes. When two or more parallel paths through the network have the same maximum duration, all of them are critical. The tool highlights every task with zero float, so all critical paths are visible.

What units should I use for duration?

Any consistent unit works — hours, days, weeks, or story points. The tool uses the numbers as-is, so just be consistent across all tasks.

What happens if I create a circular dependency?

The tool detects cycles and shows an error. A circular dependency (Task A depends on B, B depends on A) makes scheduling impossible and must be removed.

Critical Path Helper

Name: Critical Path Helper
Availability: InStock
Author: Nham Vu

Enter your project tasks with durations and dependencies to instantly see the critical path, float times, and total project duration.

Project Tasks

Task Name

Dur.

Predecessors

Legend

Critical task — zero float, cannot be delayed

Non-critical task — has slack time available

ES Earliest Start EF Earliest Finish
LS Latest Start LF Latest Finish
Float = LS − ES (days/units task can slip)

Add tasks and click Calculate
to see the critical path analysis.

Project Duration

—

Critical Tasks

—

Total Tasks

—

Critical Path Sequence

ID	Task	Dur	ES	EF	LS	LF	Float	Critical

Summary

Enter your project tasks with durations and dependencies to instantly see the critical path, float times, and total project duration.

How it works

Add each task with a name and duration (in any consistent unit — hours, days, weeks).
For each task, list its predecessor task IDs separated by commas (leave blank for tasks with no predecessors).
Click "Calculate" to run a forward pass (ES/EF) and backward pass (LS/LF) through the network.
Tasks with zero total float are highlighted as critical — they cannot be delayed without extending the project.
Review the table to see slack time on non-critical tasks and the minimum total project duration.

Use cases

Plan software releases by mapping feature dependencies and finding schedule bottlenecks.
Manage construction projects where tasks like foundation work must finish before framing begins.
Coordinate event planning activities with fixed deadlines and sequential dependencies.
Identify which tasks can safely slip without delaying a product launch.
Estimate the fastest possible completion time given all task constraints.
Communicate project risk to stakeholders by showing which tasks are critical.

Frequently Asked Questions

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Last updated: 2026-05-29 · Reviewed by Nham Vu