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Estimating time in project management: Tips and methodologies

Accurately estimating time is essential to successful project management. These time estimation strategies will start your project off on the right foot.
From Team '23

Tempo Team

PMPs aren’t the only people who manage projects. From cooking a multi-course meal for a dinner party to putting together a portfolio for a college class, life is full of tasks and subtasks that have to happen at the right time for us to achieve an end goal. 

Everyone’s guilty of the planning fallacy – underestimating how long projects and tasks will take to finish. But when you’re planning projects at work, failing to come up with accurate time estimates can have significant consequences for yourself and your team.

You don’t need a crystal ball to create a realistic project timeline. With the right tools and methodologies, you can start estimating time like a pro.

Why is estimating time necessary?

In project management, time estimation involves making realistic assessments about work timelines to predict how long it will take to complete a project, including all its individual tasks.

Here are four reasons accurate time estimates are vital:

  • Resource allocation: Understanding how long tasks will take helps you effectively allocate team members, tools, and budgets.

  • Realistic expectations: Project timelines keep clients and stakeholders up to speed on expected completion dates, avoiding unpleasant surprises or lost revenue from missed launch dates.

  • Proactive problem solving: Poor estimation can lead to last-minute rushes, compromised quality, and even project failure. Accurate time tracking helps you identify potential delays so you can take corrective action before it’s too late.

  • Greater efficiency: Estimating time encourages better time management and helps teams prioritize tasks, ensuring you maximize available resources.

Time estimation in action: A tale of two chefs

Time estimation isn’t just for managing software projects or construction sites. Imagine cooking a holiday meal, for example. Two chefs might have the same goal: prepare Thanksgiving dinner for 10 guests. However, their approaches to time estimation could lead to vastly different outcomes.

Chef A: The single-point estimator

Optimistic and a bit haphazard, this chef underestimates prep time and incorrectly assumes the cooking time printed on the turkey’s packaging is correct. 

The result: undercooked turkey and a frantic scramble to feed a hungry group of disappointed guests

Chef B: The ranged estimator

This chef draws on past experience, researches reliable recipes, and divides meal prep into individual tasks. They build in buffer time, start complex dishes early, and even delegate prep work to family members.

The result: a smoothly executed meal served on schedule to happy guests

Factors to consider when estimating time

Whether you’re assembling a project schedule for a home-cooked meal or a startup’s product launch, you should consider these three factors to ensure your time estimates are realistic:

  1. Resource availability

Lay out all the resources it will take to complete tasks on schedule. Do you have the workforce, tools, and expertise to finish the project in the desired time frame? Can you acquire any missing resources, or do you need to adjust your stakeholders’ expectations?

  1. Project scope and flexibility

How large and intricate is the project? How many dependencies could throw off tasks further down the line? Complex undertakings with a larger project scope will always require more time than simple tasks.

  1. Risk factors

What unforeseen events or obstacles could cause delays? Think of every possibility, no matter how unlikely. It’s always best to factor in some buffer time to effectively manage risks.

How to get better at estimating time

Most people see themselves as more skilled than they really are and assume the goals they set are readily achievable. Your time estimations will improve with practice, but even new project managers can put together realistic timelines by following these tips:

Look to the past

One way to avoid the planning fallacy is to gather information about similar projects you’ve finished in the past so you can compare them and make accurate projections. If you want to estimate how long it would take your employees to finish a piece of code, look at how long similar tasks have taken them before. Time-tracking software is a smart way to compile historical data to inform your estimates.

Be a pessimist

Optimism is great, but it’s often the enemy of a successful project. Assume the worst-case scenario, imagining everything that could possibly go wrong.

Don’t fall prey to wishful, single-point thinking like Chef A. Making uninformed, overly optimistic assumptions about how long something will take often leads to disappointment when unanticipated complications arise. Factor in potential delays and challenges from the get-go to make your project schedule more realistic.

Get multiple estimates

People often struggle to guess how long their own projects will take; it’s easier to make reasonable guesses about other people’s performance. An agile practice called planning poker can help determine how long a project will take. 

In planning poker, each participant gets a set of numbered cards and chooses one of them to estimate the effort for a given task. Compare and discuss these estimates to get a more accurate projection and avoid the planning fallacy.

Measure your progress

Closely track time and costs so you can see when and how your estimates begin to go off-track as the project progresses. This practice will allow you to see if your initial estimates are on target and make adjustments mid-project if things deviate. Progress measurements also serve as valuable information for any future forecasts you need to make.

4 tried-and-true time estimation methods

You don’t have to be a certified project manager to put the field’s trusted methodologies to work. Here are four of the most common methods for successfully estimating time:

  1. Critical path method

The critical path method (CPM), also known as critical path analysis, identifies the sequence of critical tasks the team must complete on time for the entire project to meet its deadline. 

  1. Three-point estimating and PERT

The program evaluation and review technique (PERT) accounts for uncertainty by creating a timeline based on three estimates (or points): the optimistic, most likely, and pessimistic expectations of how long a project will take.

The technique used to create those estimates is known as three-point estimation. Remember Chef B? Unlike Chef A, who based their timing on a single optimistic point, Chef B used ranged estimates that considered all three points to deliver a well-executed meal.

  1. Bottom-up estimation

Bottom-up estimation asks you to break down the project scope into smaller, more manageable tasks and estimate each one’s time requirements. You’ll calculate the total estimate by adding up the time expected to complete each task.

  1. Analogous estimation

Analogous estimating looks at similar past projects and uses their durations as a reference for estimating the time needed for the current project.

Bonus: Take a combined approach

Although each time estimation method has its strengths, the best approach for many projects is to use a combination of techniques.

For example, you might use bottom-up estimation to create a work breakdown structure, dividing a complex project into smaller tasks. Then, you can apply three-point estimation and the PERT method to get a range of possible completion times for each task. A multi-faceted approach helps you create the most realistic view of your project timeline.

What causes a failed time estimation?

Even with the best planning, project timelines can go awry. Here are the usual suspects:

  • Scope creep: Changes or additions to the project’s original plan that weren’t factored into initial estimates due to underestimating the project’s complexity at the outset

  • Planning focalism: The tendency to think optimistically about future tasks, ignoring the reality of how long previous similar tasks took to complete

  • Natural optimism: The natural human inclination to expect things to go smoothly, without any complications or changes

  • Motivated reasoning: Overly optimistic estimates created in response to deadlines or internal pressures from managers or other stakeholders

Improve your time estimation with Tempo

Accurately estimating time takes experience, but if you’re working in Jira, Tempo’s time tracking and resource planning software can help you understand how long tasks and projects actually take.

For an even more comprehensive overview of the project management process, try Strategic Roadmaps. This tool lets you create a visual roadmap that breaks down organizational silos and helps the whole team stay on task.