For projects that have very tight deadlines, being able to calculate the project timeline realistically becomes very important. This is because it can play a pivotal role in the success of the project. However, people often tend to misjudge the amount of time required to implement a project because they are perhaps not familiar with the type of work involved in the projects. To help them understand better, here is a guide explaining some of the best methods of project estimation that can help project managers make better time estimates.

Importance of Estimating Project Time Accurately

Accurate estimation of the project timeline is crucial in project management. Without this skill, people would not know the tentative time required to complete their projects. Hence, they would not be able to get the commitment necessary from the people who have to sign it off. More importantly, most sponsors tend to judge the success of a project by the criteria of whether it was delivered on time and within the budget or not. Therefore, to be successful, it is important to be able to negotiate sensible budgets and create achievable deadlines.

Things to Consider While Estimating Project Timeline:

External Dependencies

Every project involves many people who can be delayed, at times, for various reasons that are usually not in the control of an individual. Taking into account external dependencies at the time of planning can make getting out of the worst possible scenarios easier.

Insufficient Detail

Unknowns like insufficient level of detail occur when the project has not been thoroughly evaluated. While still in the planning stage, every detail about the project should be collected so that all the tasks could be done without any hindrance.


Some tasks involved in a project are complex. It might so happen that even after clearly defining a task, implementing it becomes difficult. When calculating the time needed to complete a specific task, it can be given a complexity rating between 1 and 3. Depending on this score, the tasks having a score of 1 can have the standard time allocation. Those with a score of 2 can have their allocated time multiplied by 1.5, and the tasks having a score of 3 can have their allocated time multiplied by 2.


People do take time off, like going on vacations, getting sick, holidays coming up, and such other things. These will no doubt inconvenience the project and they must be accounted for while creating the timeline.

Working Hours

People usually work for approximately 8 hours a day. However, their entire time is not dedicated to working on the tasks given to them. They take breaks, have lunch, go to the washroom, attend meetings, and so on. It is not fair to ask them to work every minute of the time they spend at work. That is why it is best to include these time-lapses while estimating time for the project.

Ways of Estimating Project Time Accurately

Following the below-mentioned steps can help in making accurate time estimates for the project:

Step 1: Understand What Is Required

It is very important to identify all of the work that is needed to be done when working on a project. Using various available tools to do this in greater detail is highly advisable. Also, it is important to allow time for meetings, communications, reporting, testing, and other activities that are critical for the project’s success.

Step 2: Order the Tasks and Activities

The next step is to make a list of all the activities and assign them the order in which they should be done. At this stage, it is not required to add the exact time that might be needed to accomplish these tasks. Nevertheless, it would be beneficial to note down any important deadlines.

Step 3: Decide On the Group of People to Be Involved

Just like ordering the activities, it is also very important to form a group of suitable people who should be involved in the project to make it a success. This can be done by brainstorming and asking others to contribute.

Here, choosing the people who can do the necessary work as they have certain relevant experience to draw upon is the best thing to do. Involving them would encourage them to take responsibility and ownership of the time estimates that they would come up with, and they would more likely work extra hard to meet those deadlines.

Step 4: Make the Time Estimates

The final step is to make the time estimates. There are quite a few effective methods that can help in doing this. However, irrespective of whichever method is chosen, these basic rules should be borne in mind:

  • To start with, it is essential to estimate the time required to complete each task instead of the project as a whole.
  • The level of detail involved in a particular project should depend on the circumstances. For instance, only a rough outline of time estimates should be enough for future project phases, but for the phase immediately ahead, detailed estimates need to be done.
  • Making a list of all the constraints, exclusions, and assumptions relevant to the success of the project is an important task to do. Moreover, noting any reliable data sources that can help in validating the time estimates if questioned can be helpful. It can also identify any risk areas if and when the circumstances change.
  • It is better to be prepared for future contingencies by assuming that the resources will be productive for only 80% of their time. Including extra time for unexpected events like supply problems, equipment failures, problem-solving, meetings, accidents, sickness, and such emergencies is crucial in time estimation.
  • It should also be kept in mind that people working on a part-time basis can lose significant time in switching from one role to another. Moreover, people are often too optimistic about themselves while estimating time and tend to underestimate the amount of time needed to complete the tasks.

Four Techniques Used for Estimating Project Timeline Accurately

Every person who puts together proposals formulates timelines, and creates estimates in a project is not a trained project management professional. Hence, to initiate them to the concept of project estimating, a few standard estimation techniques are explained below. These approaches can not only help in project time estimation, but also in understanding how the final cost and timeline are determined.

1)  Three-Point Estimation

This type of estimation is also known as the Program Evaluation and Review Technique (PERT). For this estimation technique, every risk associated with a project needs to be understood. They can be either good or bad. Based on these risks, three different estimates can be created, optimistic, pessimistic, and best guesses.

2)  Bottom-Up Estimation

In bottom-up estimation, the people responsible for doing the work are involved in the estimating process. This approach requires every “expert” to estimate the time they need for the deliverables the team has come up with based on the client’s request.

3)  Analogous Estimation

Analogous estimating is used when an estimate needs to be provided, but no detailed information is available on the current project. In this approach, a previously completed similar project is considered a benchmark for providing a projected total cost. Analogous estimation is possible only when there is a record of previous projects and the time and costs associated with those projects.

4)  Parametric Estimation

This estimation technique requires access to various published reports and reliable data on how much time is needed to finish a project and/or the standard hourly rates. It is an ideal approach for beginners who need to estimate a larger project accurately, without having any first-hand knowledge of the time commitments of a large-scale project. This method is also very effective for creating estimates that can be produced quickly and simply by relying on past data.


Accurately estimating the project timeline is critical in delivering any project on time and within budget. Without the said skill, it is hard to determine the time that might be required to complete the project. Getting the commitment required to achieve the project objectives from the people involved in the project might also be difficult. Moreover, agreeing to very short deadlines can prove to be a significant risk, especially considering all the stress, pain, and loss of credibility associated with it.

Therefore, to estimate project time effectively, following this four-step process can be very effective:

  1. Understand what is required.
  2. Order the tasks and activities as per priority.
  3. Decide on the group of people to be involved in the project.
  4. Plan efficiently and create the estimates.

Using a combination of the estimation methods described above to get the most accurate time estimates is also a great idea. It goes without saying that these are just a few of the multiple things that need to be considered while planning. However, this guide can help in starting with the estimation process and with time, it will come naturally.


About the Author

For 30 years, Dovico has been providing time tracking and timesheet software for clients worldwide. Manage your projects and teams, capture time and generate reports.

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