Estimating Time

Time is a valuable and finite resource. Because of this, managing time is really important, especially in today’s fast-paced world. Whether you're working on a personal project or managing a complex business initiative, accurate time estimations are crucial for success.

In this article, we'll explore the importance of time estimation, the factors that affect the accuracy of time estimates, and the best ways and practices to accurately estimate time. We’ll also talk about how time estimates differ from project cost estimates.

So, whether you're a seasoned project manager or someone who’s just starting out, this article can help you improve your future time estimations, so you use your time more efficiently.

Estimating Time
In this guide, you’ll learn:
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What Are Time Estimates? 

Time estimates are a way to predict the amount of time it will take to complete a certain task or project. They can be useful in planning and managing your time effectively, especially if you have multiple tasks to complete or deadlines to meet.

How accurately you estimate time will depend on your understanding of specific task/project requirements and your ability to complete them. The more you know about the inner workings of a particular task and/or project, the more likely it is that you’ll be to create an accurate time estimate.

As a side note, it’s important to remember that time estimates are simply estimates. They're not guarantees and may need to be adjusted as the project moves forward and new challenges arise (e.g., a co-worker gets sick, upper management decides to change directions and more.). 

However, by creating informed time estimations, you can increase your chances of completing all of your tasks and projects within a given time frame or meeting a specific deadline. 

What to Consider Before Making a Time Estimate?

These are the most important factors you need to consider to estimate time correctly:

  • Task difficulty: The more complex your task is, the longer it will take you to complete it. Consider the level of difficulty, the number of steps involved in finishing it, and any other factors that can help you determine the difficulty of a specific task/project. 
  • Level of experience: If you've completed similar tasks/projects before, you could use that information and/or experience as a reference when making time estimates. On the other hand, if you lack experience, you might want to include that when you estimate time and give yourself enough room to learn more about the inner workings of a particular project.
  • Available resources: Think about all the resources you'll need for a specific task/project, like equipment, software, or people. If you don't have access to the right resources, it may take you more time to complete a task/project, so it will affect the way you estimate time.
  • Potential roadblocks/obstacles: Try to identify potential obstacles and challenges that could slow you down (e.g., technical issues, communication barriers, or unexpected delays). This will help you make contingency plans and adjust your time estimations accordingly.
  • Deadline or due date: If you have a deadline to meet, make sure to take that into account when making time estimates. Be realistic and plan accordingly.
  • Other commitments: Consider any other commitments you have, such as meetings, appointments, or other tasks. This will help you plan your time more effectively and avoid overcommitting yourself.
How to make time estimates

How to Make Time Estimates?

To make time estimates, you should do the following:

  • Identify all the steps required to finish the task/project and break it down into smaller components.
  • Estimate the time for each component. Consider the complexity of each component while taking into account your experience level to estimate how long it will take you to complete each step. Be sure to account for any potential roadblocks.
  • Add up the component times to get an overall estimate of how long it will take you to complete the whole thing.
  • Pad the estimate. Add some extra time to your estimate to account for unexpected delays or complications. This will help you avoid feeling rushed or overwhelmed and give you a buffer in case something unexpected happens.
  • Review and adjust the estimate. Ask yourself if it's realistic. If not, adjust it accordingly. Consider how you can optimize it or whether you need to re-evaluate the task components to improve your time estimate.
  • Monitor your progress. As you work on a particular task/project, monitor your progress and adjust your time estimate if necessary. This will help you stay on track and make changes to meet deadlines or extend them if needed, not to mention that it will equip you with the knowledge you need to make a better time estimate next time.

How to Avoid Underestimating the Time You Need

A big challenge in estimating time is people’s tendency to underestimate the amount of time certain tasks will take. They do so often enough that psychologists have developed a term for it — “planning fallacy.”

The concept of the planning fallacy was first introduced by psychologists Daniel Kahneman and Amos Tversky, who are often referred to as the “fathers of behavioral economics.”

In their research, Daniel and Amos described how people tend to completely overlook historical data when making time estimations (i.e., how long will a certain task take to complete). 

What people typically do when making a time estimation is focus on the task at hand (e.g., writing) and then make estimates based on that, ignoring the historical data (e.g., how long it took to write a text of similar complexity and length last time).

Daniel Kahneman went even further and expanded on the original idea formulated by the two psychologists by asserting that the most common reason for time estimation mistakes can be ascribed to: 

  • Neglecting to consider historical data, i.e., the length of time it took to finish similar tasks in the past
  • Working under the assumption that there won’t be any obstacles or interruptions during our work time

Mistake number 2 is, again, an extremely common occurrence amongst the human population and has a psychological term attributed to it — optimism bias. Optimism bias is explained as our tendency to feel that things will get better/easier in the future. 

So our optimism bias, which is likely hardwired into the human psyche, leads us to make the “planning fallacy” when we’re estimating time, as it pushes us into believing that tasks that we’ve already completed won’t take as long in the future. This inevitably leads us to underestimate the amount of time certain tasks or assignments will take to complete. 

However, there are strategies we can employ to counteract the effects of the planning fallacy.

4 steps to avoid the planning fallacy

How to Avoid the Planning Fallacy?

  1. Use historical data: Track the time you spend on your tasks. If you ever find yourself doing a task that’s similar to one you’ve done before, use the data you have on the former to estimate how long the latter will take.
  2. A friend in need is a friend indeed: Have someone else estimate time for you. Preferably a person that knows you and the type of work/tasks you are doing. 
  3. Use a three-point estimation method: Estimate the best-case scenario, worst-case scenario, and most likely scenario for each task or component. Add those numbers up, divide them by 3, and you’ll get a good estimate based on their average. 
  4. Estimate when you don’t feel optimistic? A study that analyzed Twitter users determined that a lot of people have what’s called a ”trough,” or part of their day where they don’t feel optimistic. For most people, that time is around mid-day. Basically, to avoid the planning fallacy, you should make estimates when you don’t feel optimistic or are in your daily “trough.”

The Difference Between Time and Project Cost Estimation

A term that is often used in the same context as time estimation is project cost estimation. 

Time estimation and project cost estimation are two different but closely related processes.

The key difference between time and project cost estimation is the focus of each process. Time estimation focuses on estimating the amount of time required to complete a project, while project cost estimation focuses on estimating the financial resources required to complete a project

Project cost estimation is the process of calculating and predicting how much it will cost to complete a certain project to help develop a budget for a project. This can help project managers plan, allocate resources, and track expenses in the most efficient way possible.

This process includes identifying all the costs associated with a particular project, such as:

  • Labor
  • Materials
  • Equipment
  • Overhead
  • Travel
  • Training and development
  • Marketing
  • Legal costs

The specific costs associated with a project will depend on the nature and scope of the project, as well as the industry, the area/country where the company or team is located, and more. 

While both time and project cost estimation can help you define the project scope, access whether a project is financially beneficial, and identify potential issues or risks, time estimation is the more abstract of the two, as it only concerns itself with the resource of time, which makes it harder to execute. 

However, it’s important on both a personal and professional level.

5 activities closely related to time estimates

Why Are Time Estimates Important?


Time estimates help project managers and team members plan a project by identifying the tasks that need to be completed, the order in which they need to be completed, and the timeline for completing them. Accurate time estimations ensure the project stays on track and is completed within the given time frame.

Resource Allocation

Time estimates help project managers allocate resources, such as personnel, equipment, materials, and more. By knowing the amount of time required for each task, project managers can ensure that the necessary resources are in fact available when they need them.


Time estimates help project managers develop an accurate budget for the project. With accurate time estimates, managers can ensure that the project is completed within the available financial restrictions while avoiding cost overruns.

Monitoring and Tracking

Time estimates provide a baseline against which project managers can measure and track progress. By tracking the actual time it takes to complete tasks against the estimated time, project managers can identify potential delays or issues and take corrective actions to keep a specific project on track.


Time estimates help communicate a project’s timeline to stakeholders, upper management, clients, and team members. This ensures that everyone involved in the project will have a clear understanding of what needs to be done and when.