What is the best tool to calculate the critical path on a project?

The critical chain method is a scheduling technique that accounts for resource constraints and uses buffers to protect the project completion date - it is an alternative scheduling approach, not a tool for calculating the critical path.

A GERT diagram supports probabilistic and conditional branching in schedules but is rarely used in practice and is not the standard tool for critical path calculation.

A Gantt chart displays activities on a timeline bar chart and can show the critical path after it is calculated, but it does not provide the dependency network structure needed to calculate it.

The project network diagram depicts all project activities as nodes or arrows connected by dependency relationships, providing the complete logical sequence required to perform Critical Path Method (CPM) analysis. By tracing all paths through the network and calculating Early Start, Early Finish, Late Start, and Late Finish dates, the project manager can identify the longest path - the critical path - and determine float for each activity. No other tool provides this complete dependency mapping required for CPM.