Calculating the Estimated Time To Completion of a Project

Estimated time to complete is a value that is expressed in hours of work required to complete a task or project. During the initial stages of project planning one of the main objectives is to get a realistic estimation of time to complete. Estimating the time to complete is one component of the project plan.

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Methods for estimating time

The approaches for calculating the ETC of your project are listed below, along with the benefits and drawbacks of each approach:

Top-down estimating

In top-down estimating, you first establish the overall project timeline, frequently basing this timing on professional opinions. Then, according to the overall timing, you allocate time for various tasks.

When you are submitting time and cost estimates in the early stages of a project, when the timeline is still somewhat uncertain, top-down estimating can be helpful. However, the project estimate as a whole, which can be inaccurate, heavily influences the effectiveness of this method.

Bottom-up estimating

The bottom-up method starts with segmenting the project into distinct parts and estimating the time required to complete each as the opposite of top-down estimating. The total of the individual estimates would represent the project’s overall time estimate.

Bottom-up estimating can be more accurate than top-down estimating, but it takes more time and research to dissect the overall project into its component parts. This approach may also overlook the possibility of some activities being integrated, which could result in an overestimation of timing and costs.

Comparative estimating

Comparative estimating, also referred to as analogous estimating, involves analyzing the timing of previous projects that are similar to the current project and using that estimate as a guide. If your current project is a campaign to launch a new beverage and a prior campaign to launch a new clothing line took six months, for instance, you could predict that the current project will likely take about six months.

Comparative estimating is fast and based on historical data. However, because it does not take into account differences between projects, it may be inaccurate.

Parametric estimating

When estimating the time needed for a single task, multiply that time by the number of related tasks the project entails. You can estimate a total of two hours if, for instance, you can estimate that a meeting will last 30 minutes and you have five meetings scheduled this week. 5 hours worth of meetings this week.

If you can base your estimates on historical data, parametric estimating can produce estimates that are reasonably accurate, but some groups of tasks may have timing variations that an equation can’t account for.

Three-point estimating

You determine three estimates rather than just one: the most likely estimate, the most optimistic estimate, and the most likely estimate. The optimistic estimate is based on the ideal situation, in which everything goes as planned. The negative estimate assumes that all anticipated risks materialize. The most likely scenario is somewhere between the two extremes.

By averaging the optimistic and pessimistic estimates, you can determine which estimate is the most likely. Normally, calculating the three estimates entails extensive analysis and takes a lot of time, but the results are accurate.

Why is it important to estimate time correctly?

Correct time estimates can enhance your reputation in the industry and lessen stress at work. When the ETC is accurate, you’ll probably be able to find enough money, people, and resources to finish the project satisfactorily for your clients or employers, possibly opening up more project management opportunities in the future. A correct ETC also helps project managers design fair scheduling. The project’s participants will likely not need to put in extra hours to deliver high-quality results and meet project deadlines, creating a more enjoyable working environment for them.

How to estimate time correctly

Make accurate time estimates for project completion by following these steps:

1. Consult historical data

Often, it’s beneficial to look at the schedules of related projects to figure out the ETC of your own. As an illustration, if you are in charge of overseeing the construction of an eight-story building, you could review the schedules of previous construction projects that had requirements similar to yours. The average time for laying a foundation has been six days, and construction has lasted up to a year, though you may not find information about every aspect of the process. With this information, you can calculate that finishing your own construction project could take more than a year.

2. Determine the requirements

Finding out how much work the project requires, including the repetitive tasks of meetings, correspondence, reports, and testing, is the first step in time estimation. Try writing down all the tasks in a list with no particular order. You can get a general idea of how to divide the work up in terms of time and personnel by looking at the total number of processes.

Project specifications also cover the team that works on completing the project. Determine who you intend to involve in the project’s decision-making levels at this point, as well as what their potential individual roles might be. They might even add to the list of tasks and give a more accurate idea of the amount of work required.

3. Order the steps

It’s time to order the activities from the project’s beginning to its conclusion once you’ve identified all of the necessary ones. Although you can postpone determining a time estimate for each activity at this time, you might note significant milestones that must be met. It would be a good idea to emphasize obtaining permits before a specific date, for instance, if there is a deadline for the permits you require for the project to advance past a certain stage.

4. Assess potential risks

Risks can cause substantial delays in a project’s schedule, which may force you to go over budget or reschedule the work to stay on schedule. For instance, bad weather can cause delays in construction projects and introduce additional risks like mold or the inability to access construction zones. Adding time to the overall schedule to account for potential weather delays or creating contingency schedules to lessen the effects of such delays would be beneficial. These actions could help you regain some control over the project and your ability to finish it on schedule.

5. Make the estimates

You can estimate the time required to complete the project using the techniques previously discussed while taking into account the data you’ve collected, the requirements and personnel you’ve determined, and any potential risks that may arise. You may find it useful to combine methods. Comparative estimating, for instance, can work well with top-down and bottom-up methods, improving their accuracy by giving calculations a historical foundation.

Using the premise that your initial estimates may be conservative, you can prevent underestimation regardless of the methods you select by adjusting the estimates as necessary but within reason. For instance, you may have initially estimated that it would take five days to transport the materials, but a single-day delay could mean that you would have to wait until business days resumed in order to receive the materials. If so, you might think about planning on at least seven days for that activity.

Don’t forget to utilize any technology available to you to complete your work. Spreadsheet applications frequently include project estimation tools that can be useful in providing calculating features to help you make more accurate estimates.

6. Create and maintain your timeline

Finally, you can display your ETC in a project timeline that is simple to read. So that everyone is aware of the expectations, share the timeline with your team and clients. As the project progresses, don’t forget to emphasize to your team how important it is to mark progress on the timelines.


How do you calculate estimated time?

To estimate time effectively, follow this four-step process:
  1. Understand what’s required.
  2. Prioritize activities and tasks.
  3. Decide who you need to involve.
  4. Do your estimates.

Why do we estimate time?

You have a much higher chance of meeting the deadline for your task if you have an accurate estimate of how long it will take. Knowing how long a task will take can help you schedule your day and make sure you get everything done, even if it doesn’t have a deadline.

How do you estimate time in a project?

How to estimate project hours
  1. Review project scope. …
  2. Create a list of tasks. …
  3. Collect data for each task. …
  4. Include external hours. …
  5. Consider revision hours. …
  6. Consider adding contingency hours. …
  7. Add all components together. …
  8. Review and revise the estimate.

How do you calculate estimate?

How to estimate project hours
  1. Review project scope. …
  2. Create a list of tasks. …
  3. Collect data for each task. …
  4. Include external hours. …
  5. Consider revision hours. …
  6. Consider adding contingency hours. …
  7. Add all components together. …
  8. Review and revise the estimate.

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