Sporkforge offers a free online critical path method calculator that has the look and feel of a standard calculator. To operate this calculator, the project manager manually enters the name of each task, the task's expected duration, and the name of any predecessor tasks. However, information must be entered precisely as follows or the CPM calculator will fail to return any results.
- Quotes must be used around a task name that contains any spaces or tabs. (For example "Task A" versus A, where the quote would be optional).
- Duration time units must be generic (1, 2, 3, etc.) and uniform for all task entries. The start times reported in the results assume a project start time of 0.
- The task list must be entered in the text box provided, or uploaded as a text file in the same format. There is a 5 megabyte file size limit.
- This tool has a limit of 1,000 project tasks.
After entering the critical path information from the sample project network diagram appearing at the beginning of this article, Sporkforge returns this report.
Microsoft Excel - With a little ingenuity, you can also create a critical path method calculator in an Excel spreadsheet. This article on use of Excel as a CPM calculator walks you through the steps and it only takes a few minutes to set up the template. After entering the tasks and designating the six different paths in our example project, the Excel spreadsheet produces the same critical path information as the Sporkforge calculator and has this appearance.
Microsoft Project creates a similar report with the added bonus of a having a Gantt chart to visually display the critical path and slack time shown in red and by line extensions, respectively. Microsoft Project also makes it easy to insert critical path milestones to highlight these noteworthy achievements. To create the critical path diagram, select the Gantt chart view, enter the names of the tasks, the duration of each task, the predecessors (located under advanced settings), and then check the boxes for the critical path and slack time. The results of our example are displayed in this format.
You can also generate a summary report by selecting the critical path from the reports catalog.