People still use Gantt charts today

How to make a Gantt chart

On this page we explain how to create a Gantt chart. The description of the concept of the Gantt chart can be found here: What is a Gantt chart?

Gantt charts are created with PMIS (Project Management Information System) applications such as Primavera Project Planner®, Microsoft Project® or MindView®. A typical approach to creating a schedule is to hold meetings with selected members of the project team and identify activities. While this approach results in a schedule, it may not be a complete schedule. A complete schedule contains all the activities that are necessary to ensure compliance with the 100% rule. The 100% rule requires that the area baseline cover 100% of the project scope. The basic scope components are the main sources for identifying the schedule activities. If the area baseline addresses 100% of the project scope, the schedule activities also address 100% of the project scope. So, following these steps will ensure that the final project plan is actually a complete schedule

6 steps to the Gantt chart

Step 1 - Check the scope baseline

Call the team together and review the approved scope baseline, which consists of three components: 1) the scope statement, 2) the work breakdown structure (WBS) and 3) the PSP dictionary. The project team member should confirm that the scope baseline covers 100% of the project scope.

Step 2 - define activities

Using a technique called "dismantling", the project team divides each PSP work package into individual activities. Just like when creating the WBS work packages, the team must establish rules for creating schedule activities. The final schedule must be effective and efficient. Too many activities can be just as negative as too few. It is also important to identify deadlines and milestones as you break down the project.

Gantt chart passing deadlines

Step 3 - order of activities

Each activity relates to one or more other activities. Every activity except the first and the last has a relationship with a predecessor and a successor. Order of activities means that the activities are put in the correct order using the correct relationships. There are four types of relationships:

  • 1. End - beginning - The successor activity can only be started when the predecessor is finished.
  • 2. Beginning - beginning - The successor activity cannot be started until the predecessor has been started.
  • 3. Beginning - end - The successor activity cannot be ended until the predecessor has started.
  • 4.End - end - The successor activity can only be ended when the predecessor is finished.

Relationships 1 and 2 are the most commonly used. End-beginning is a sequential relationship, beginning-beginning is a typical parallel or overlapping relationship.

Gantt chart dependencies

Step 4 - estimate resources

Before the duration can be estimated, resources must be identified and estimated. Resources include manpower, materials, and equipment. Various estimation techniques are used, including analog, parametric, three-point, and bottom-up. Skills, competencies and technologies are key factors to consider when making the estimate. After estimating the resources, they are loaded into the schedule for the respective activities. A resource calendar is also created to show when resources are needed and available.

Step 5 - Estimate duration

Duration is the time between the start and the end of an activity. Review the resources, relationships, and sequence, and estimate the duration for each activity. The same estimation techniques that are used to estimate resources can be used to estimate duration. However, be sure to identify conditions that are limitations or restrictions on an activity.

Gantt chart constraints

Step 6 - Develop a schedule

Create the Gantt chart by loading all of the information into a project management software tool. Review the schedule and ensure that all schedule risks have been considered. Verify that it includes response plans and contingent liabilities. A typical way to fix contingencies on the schedule is to add buffers at the activity level, project level, or both. A buffer is an activity with no resources or scope to provide additional time and reduce schedule risks. Resource optimization techniques such as smoothing or leveling resources are used to create realistic schedules. Review and approve the schedule. The approved Gantt chart plan becomes the baseline of the schedule.

How to work with a Gantt chart

The Gantt Chart schedule baseline is the formal document used to run, monitor, and control project schedule performance. The members of the project team were assigned work packages in the work breakdown structure. The respective team members evaluate their work package activities using a disciplined method. There are two commonly used statusing methods: 1) Percentage of work done and 2) Earned Value Management System (EVMS). The former is easy to use but can be subjective. EVMS, on the other hand, measures schedule performance based on the value of work done.

Actual schedule performance is compared to planned performance to identify any discrepancies. Particular attention is paid to the activities of the critical path. The critical path is the longest path on the schedule and has no buffer. This is called critical because any delay in any critical path activity results in a corresponding delay in the project end date. The critical path is usually colored red when shown on Gantt charts. If the variance exceeds a set threshold, the project team must consider taking either preventative or corrective action. Only if the deviation cannot be adequately taken into account by these measures should the project team issue a change request to formally change the baseline.

Critical path shown in red

A number of techniques are available to take action to correct the discrepancy. The project team can add leads or lags. A lead is an intentional adjustment of an activity by setting the start date earlier than originally planned. A lead can be used to speed up the schedule. However, the schedule risk is usually increased. Likewise, a delay is an intentional adjustment to an activity that delays the start date. When working with a lead or lag, the schedule relationship stays the same. When only schedule acceleration is required, two techniques are used without reducing the scope. These two techniques are: 1) Fast Tracking and 2) Crashing. Fast tracking increases the overlap of activities and can lead to increased risk. Crashing requires more resources and could lead to increased costs.

Another use of a Gantt chart is to predict schedule performance. Gantt charts are great tools for predicting project plans. Many of these offer forecasting methods to calculate the estimate to completion. Earned value techniques are also included in many forecasting planning applications.