Estimating Time

Time is a valuable and finite resource, and it’s what makes managing time really important, especially in today’s fast-paced world. Whether you're working on a personal project or managing a complex business initiative, estimating time accurately is crucial for success.

In this article, we'll explore the importance of estimating time, the factors that can affect the accuracy of your estimates, and the best ways and practices for accurately estimating time. 

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

Estimating Time
In this guide, you’ll learn:
  1. Text Link
  2. Text Link
  3. Text Link

 What Is Time Estimation?

Time estimations are used as 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're estimating 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 estimation.

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 estimating time in an informed way, you can increase your chances of meeting a specific deadline or completing all of your tasks and projects within a given time frame. 

Estimating Time: Factors to Determine Task Duration

Things to consider before making time estimates

These are the most important factors you need to consider when estimating time for specific tasks:

  • 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. 
  • Level of experience: If you've completed similar tasks before, you could use that information and/or experience as a reference when making a new time estimation. On the other hand, if you lack experience, you might want to include that when estimating time and give yourself enough room to learn more about the inner workings of that particular task.
  • Available resources: Think about all the resources you'll need for a specific task, 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, and that 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.

6 Steps to Improve Your Task Time Estimation

4 steps to avoid the planning fallacy

To make time estimates, you should do the following:

Step 1: Identify all the stages required to finish the task and break them down into smaller components.

Step 2: Estimate the time for each component. Consider the complexity of each component while taking into account your experience level to roughly calculate how long it will take you to complete each step. Be sure to account for any potential roadblocks. And, if you want to make this part of the estimate more accurate you could use a time-tracking app to gather data about task duration and its complexity.  

Step 3: Add up the component times to get an overall estimate of how long it will take you to complete the whole thing.

Step 4: 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.

Step 5: 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 estimation.

Step 6: Monitor your progress. As you work on a particular task, 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.

Time Estimation Methods 

Time estimation methods

There are numerous techniques and methods that can be used to accurately estimate time. Some of the most well-known are bottom-up estimation, analogous estimation, and three-point estimation:

Bottom-up Estimation

Bottom-up time estimation is a project management technique in which the duration of every individual task is estimated separately. Once they complete this step, managers can then add those estimates to calculate the approximate duration of an entire project. This method is predominantly used when the tasks are clear, defined, and can be broken down into smaller components. 

Top-Down Estimation

Top-down estimation allows managers to estimate time for the project’s total duration by: 

  • Using historical data (from similar projects done in the past); 
  • Hiring an expert consultant (who has worked on similar projects in the past);
  • Making an educated guess.

Top-down estimation is not known for being overly accurate. It’s mostly used as a preliminary means to estimate time and provide a company with a rough outline of how long a project could take. The main goal of this method is to give businesses a quick and easy way to evaluate if a particular project is going to be feasible and whether or not they should invest more time and resources into said project.

Analogous Estimation 

The analogous time estimation method is very similar to top-down, and it’s used in project management as a means to create a rough estimate for a project’s duration. It uses historical data from similar projects done in the past to create a ball-park estimate for the duration of a current project. 

The accuracy of an analogous estimation is directly correlated to the accuracy of the data used to create it. Meaning, the more precise information about past projects the company has, the more accurate this estimate will be. For example, if a company is using a time-tracking app to track task duration, the analogous estimation they make will be more realistic than if the opposite was true.

Three-Point Estimation

The Three-Point method is used to estimate time for projects or tasks. The estimation takes into account 3 different scenarios (estimates):

  • Best-case scenario;
  • Worst-case scenario;
  • Most likely scenario.

After estimating the time for each, managers can then use one of the two formulas to calculate the final estimate (E). 

The first one puts an emphasis on the most likely scenario and it goes:

E = (O + 4M +P) / 6

The other formula incorporates probability and aims to find the Standard Deviation (SD) and completely ignores the most likely scenario. It goes:

SD = (P - O) / 6

Example of a Time Estimation

Next, we’ll show you how to estimate time using the Three-Point method! 

Let’s say that you’ve done a similar project to the one you’re working on now in the past, that you’ve collected the data about task duration, and that you understand the ins and outs of said project. Let’s also say that a similar project had exactly 100 tasks and that they collectively took 100 hours to complete. 

With that information, we can start making the initial 3 estimates (or scenarios):

  • Most likely scenario (M) = 100 tasks = 100 work hours; (this scenario assumes that nothing is going to be different from the last project);
  • Best case scenario (O) = 100 tasks = 70 work hours; (this scenario assumes that because you’ve done a similar project before, you’ll be able to do this one faster);
  • Worst case scenario (P) = 100 tasks = 110 work hours (this scenario assumes that everything that things can go wrong and accounts for scope creep);

Now that we have the initial estimates, we can add those numbers to a formula and make the final estimate.

E = (O + 4M +P) / 6

E = (70h + 4 x 100h + 140h) / 6

E = 610h / 6 = 101,6h

And there you have it, your final time estimation predicts that you will have to put in 101,6 work hours to complete the new project.

Why Is Estimating Time Important?

Why are time estimates important?


Estimating time helps 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. Making an accurate time estimation ensures 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.


Estimating time helps 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

Estimating time provides a baseline against which project managers can measure and track progress. By tracking the 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.


Estimating time helps 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.

Additional Tips for Estimating Time

Use Time Tracking Software

Using time-tracking software is a great way to gather accurate data about the duration of individual tasks. This can help you analyze the quality of your current estimates but also aid you in your future time estimates by giving you the necessary data you can later use to your advantage.

Don’t Forget to Break Down Tasks

Every task, even if seemingly extremely difficult, can be broken down into smaller and more manageable components. One of the benefits of doing this is that it can make the whole process of estimating time much easier. Why? Because instead of making a time estimation for a really big task (which can feel overwhelming), you can just make time estimates for a couple of smaller tasks. After you do that, just add the numbers up to get a full-time estimation for the larger task.

Analyze and Learn From It

Estimating time is not an exact science, so to speak. In fact, it’s one of those things that the more you do and the more data you gather, the chances are you’ll become better at it. But, to actually improve your time estimation skill, you have to regularly analyze and review your time estimates. The easiest way to do this is to compare your original time estimation for a particular task to the actual amount of time it took you to complete it. 


What are the three types of time estimation?

Three types of time estimation are:

  • Neutral – estimation that doesn't presume anything in particular;
  • Pessimistic – estimation that presumes there will be a lot of problems;
  • Optimistic – estimation that presumes everything will go smoothly;

What is the estimated time to complete (ETC)?

Estimated time to complete (ETC) is a commonly used project management metric. It represents the amount of estimated time that’s needed to complete the remaining work (project or task). The ETC metric is used to predict the amount of additional time required to finish a project or task. The calculation can either be done based on current progress or historical data.

How to calculate ETC?

There are several ways to calculate ETC or Estimate Time to Complete. One of them can be performed by reversing the formula for Estimate at Completion (EAC). 

EAC = actual costs (AC) + Estimate to Complete (ETC)


Another way to calculate ETC is by subtracting the Original Budget (BAC) from the Actual Costs (AC). For that, you can use the formula:


Why are time estimates important?
Why are time estimates important?
Why are time estimates important?