excel gantt chart template with predecessors free

Excel gantt chart template with predecessors free update#
Excel gantt chart template with predecessors free free#

What are Predecessors and Successors?Ī predecessor is a task that must be completed before its successor task can start, without any other tasks in between. O-M-P helps calculate the expected duration for each task, and those expected durations are used to calculate the expected Minimum Time to Complete (but not the overall uncertainy). Note: The O-M-P approach does not give you an expected range or distribution for the Minimum Time to Complete the project. You can just enter the Most Likely times if you don't want to account for uncertainty. This lets you account for some uncertainty in your estimates. The statistical aspect of PERT is implemented in the spreadsheet by allowing you to enter O-M-P times ( Optimistic, Most Likely, and Pessimistic). The terms I am using in the spreadsheet, such as critical path, predecessor, successor, float and slack come from PERT.ĬPM and PERT are commonly used together, but PERT includes a statistical approach that doesn't necessarily need to be part of a critical path analysis. For more detail, see the wikipedia article. What I am calling the PERT algorithm is the logical and mathematical means for calculating the minimum time to complete a project, based on the Program Evaluation and Review Technique developed in the 1950s by the US Navy. This spreadsheet does not allow you to enter those types of constraints, so for the purposes of the spreadsheet, a critical task is simply defined as a task with zero slack time. Note: A constraint such as not being able to start a task until a certain time of day could cause what would have been a critical task to have some slack time (because of having to wait for a certain time of day to start the next task). For example, if the second task could be delayed 5 hours, then the first one could be delayed 2 hours and the second task could still be delayed 3 hours. That definition is based on the fact that if you delay or increase the duration of a critical task, it will cause the project to take longer.Ī critical task is not necessarily a task that has another task immediately following it, because if the second task has slack time, then the first one might also. What is a Critical Task?Ī critical task is a task that has zero slack time. In addition to identifying critical tasks, calculating slack time can help identify tasks that can be delayed, allowing a project manager to make decisions about where to allocate resources. Slack or float time is the amount of time the task can be delayed without causing the overall project to take longer.

The PERT algorithm calculates the slack time or float time for each task. This spreadsheet finds the critical path using the PERT algorithm. There can be multiple parallel critical paths, and the critical path may change if you are able to reduce the duration of one of the critical tasks. In other words, unless you can reduce the duration of one or more tasks on the critical path, you can't reduce the time your project will take. The critical path is the string of dependent tasks that limit a project from being completed faster. This is a simple yet huge breakthrough that makes the spreadsheet a lot easier to use.

Excel gantt chart template with predecessors free update#

Update - The new version 1.2 uses an updated algorithm that assumes all tasks have the Finish task as a successor. Task dependencies are defined by simply listing the predecessors for each task.

Excel gantt chart template with predecessors free free#

Milestones (tasks with zero duration) are shown as black diamonds, but you don't have to mess with the axis scaling like the free version. The Gantt Chart shows the tasks on the Critical Path as red bars, the flexible tasks as blue bars, and the slack time as gray bar extensions. You can choose to calculate the expected time (Duration) using either the Triangular or Beta distribution. Unlike a normal project schedule or gantt chart, this spreadsheet lets you use the statistical aspect of the PERT algorithm by defining the duration of a task using O-M-P times (Optimistic, Most Likely, and Pessimistic). This version lets you include up to 500 tasks (more upon request, if necessary). This spreadsheet implements the PERT algorithm and Critical Path Method to aid in project planning and scheduling.