What Is The Planning Fallacy and How To Beat It Down? (9 Useful Tips)

written by Dan Silvestre
Productivity, Time Management

planning fallacyThe planning fallacy is a prediction phenomenon. It occurs that people underestimate the time it will take them to complete a task. 

It’s all too familiar to many of us. 

…and it continues despite knowing that previous tasks have taken longer than planned.

The planning fallacy was first proposed by Daniel Kahneman and Amos Tversky. They presented their theory in an influential 1979 paper.

Let me explain.

The study “Exploring the “Planning Fallacy”: Why People Underestimate Their Task Completion Times”:

“37 psychology students were asked to estimate how long it would take to finish their senior theses. The average estimate was 33.9 days. They also estimated how long it would take “if everything went as well as it possibly could” (averaging 27.4 days) and “if everything went as poorly as it possibly could” (averaging 48.6 days). The average actual completion time was 55.5 days, with only about 30% of the students completing their thesis in the amount of time they predicted”.

Turns out students’ actual completion time was a remarkable 21.6 days longer than their best estimate (55.5 days to 33.9 days).

Other scientists, in “An Economic Model of The Planning Fallacy” (2008), say:

Faced with an unpleasant task, people tend both to underestimate the time necessary to complete the task and to postpone working on the task. Thus projects often take inordinately long to complete and people struggle to meet, or even miss, deadlines”.


Why Does it Happen and How to Beat it? 

Let’s see why we assume we have more time than we actually do

Then we will fix it in an instant.

The planning fallacy can make it difficult for us to complete tasks. Things like: 

  • being on time for a meeting
  • meeting the application deadlines for college scholarships
  • getting ready for your plane departure
  • filing taxes
  • doing referee reports
  • planning for retirement
  • making investments in your health

…and many others (also referred to as “life”).

The planning fallacy can influence your health and work satisfaction

Assuming you have more time than you do is the quickest route to:

  • stress 
  • overwork 
  • a lack of productivity 
  • burnout

Consider that Mr. Average and the Sydney Opera House are in the same boat when it comes to the planning fallacy. The Australian government first commissioned the project in 1958. They set the expected completion date for 1963. Yet, it didn’t open until 1973 – 10 years late.

Happens to the best of us.

Planning Fallacy — 9 Ways to Overcome it

What if you could fix the cognitive bias that causes the planning fallacy to happen?

Let’s break it down.

Below, you’ll find 9 ways to overcome this cognitive bias

1. Take an Outside View

Kahneman and Tversky believe that people lean towards an “inside view”.

They focus on the specifics of the task at hand, paying special attention to its unique features. 

For example: 

People imagine and plan out the specific steps they will take to carry out the target project. 

Do you know what’s the problem here?

Events usually don’t unfold exactly as we imagine (not to mention — never).

We love to create a thoughtful mental scenario in advance, but we will likely encounter: 

  • unexpected obstacles 
  • delays
  • interruptions 

Try to make more realistic predictions. Take an “outside view”. Be smarter than your cognitive bias.

Overcome your own (incorrect) subjectivity. 

Do not base your estimates on your own frame of reference .

Base your predictions on your prior experiences so you don’t fall into the trap of thinking that your previous experiences aren’t relevant to the new task.

Here’s what happens:

People recognize that their past predictions have been over-optimistic. 

Yet, they insist that their current predictions are realistic.

We are complicated creatures, aren’t we?

2. Be a Pessimist

What can go wrong, will go wrong — states Murphy’s Law.

Sad as it seems, it’s pretty useful when you have work to do

Your projects won’t run perfectly, even with your best intentions at heart. 

Approaching planning from a “negative”, i.e. risk management standpoint will help curb enthusiasm.

Here is some handy advice to follow:

  • Set a realistic deadline. Add a little buffer time (for example 20 percent to your estimated time) to that. Recalculate as needed
  • Focus on your lists. Only spend time and energy on what needs to get done
  • Consider what could go wrong. Think of how you can respond

3. Resist the Autocracy of the Urgent

Kat Boogaard of Trello explains:

“Our brains have the not-so-helpful tendency to conflate real, productive work with those other small, menial, and mindless tasks. By totally pushing those out of your mind (and off your to-do list) for now, you won’t be tempted to color-code your inbox when you should actually be completing that presentation that’s due in two hours.”

We tend to put important tasks aside and deal with urgent tasks.


Because they provide us a rapid sense of accomplishment and this is what tigers like. 

Urgent tasks need your immediate attention. Phone calls, meetings, tasks with tight deadlines – they want you to take quick action.

These tasks don’t help advance long-term goals. Important tasks do. 

To solve this vicious cycle, understand the difference between urgent and important tasks.

How good you are at distinguishing urgent and important tasks influences your future success. 

4. Make Use of the Pomodoro Technique

Let’s jump right in:

For many people, time is an enemysays Francesco Cirillo.

He’s an Italian entrepreneur, creator of the time management know-how called Pomodoro technique.

When Cirillo was a student, he created his own simple study habit. He used it to maximize his productivity and reduce a feeling of burnout.

It’s all about tracking your time to get a more realistic handle on your projects. Especially on how long specific projects and tasks take you.  

The Pomodoro technique teaches us to work with time, not against it

How to put it into practice?

This technique focuses on working in short, focused bursts of 20/30/40 minutes. Then you give yourself a brief break to recover and start over.

The technique requires a timer. It allows you to break down your large complex task into manageable intervals

Once you start a task, you aim to finish it before attending to urgent but unimportant tasks.

5. Declutter of “Time Bullies”

Your working time is special. It’s important. Care about it. 

When you work, your time is for your work. Stick to it.

Say “no” to unwanted cigarette breaks and gossiping with office co-workers.

Let’s say it again: When you work, you work.

Learn to say “no” to those who don’t respect it. 

Saying “no” gives you time to focus on your creative efforts. 

Don’t get suckered into tasks or leisure you don’t have time for.

It may be hard sometimes but use your assertive skills. Know how important is the working time for the development of your idea. 

Say “yes” or “no” when you mean it.

6. Break Big Tasks Into Smaller Onesplanning fallacy break tasks

This rule re-appears on many occasions and it’s always very useful.  

People who procrastinate often feel overwhelmed. The task seems undoable and evokes feelings of frustration. 

And why is it? 

Often because it’s a large, difficult block of stuff to do, a huge, heavy rock.

But here’s the good news:

You can break this rock into nicer, doable pieces

When you make predictions about your task, pay attention to the steps you need to take.

Don’t focus only on the outcome.

It gets better. 

The more steps your task or project involves, the more opportunities for something to go wrong. 

By breaking a bigger project into smaller tasks, the work is more manageable. 

It’s also less intimidating from the beginning. In other words, it’s easier to crack

Step-by-step this is how you win even the biggest projects.

If your task is too hard or large, break it into smaller tasks. Time-box these smaller tasks.

Set a specific goal for the end of that length of time, and set it in stone.

If you set a tighter deadline for each of your tasks, it will inspire you. You are going to find the most productive way to meet those deadlines and get your work done.

Make a list of the tasks you need to do by close of day today and think how much time it will take for each of them.

Find yourself racing against the clock. This is exactly what you want. 

You want to accomplish things, not just work. 

When you’re done, take a look back and see how you’ve fared. Measure your progress. See if your assessment of the time needed was correct. Learn from your mistakes. 

Work better, faster, and smarter.

7. Let Yourself Detach From the Original Plan

Many cognitive biases mess with time management. 

Anchoring is another type of cognitive bias. It plays a big role in the planning fallacy. 

Anchoring (coined by Muzafer Sherif, Daniel Taub, and Carl Hovland) is the tendency to rely on early information. 

You depend on information gathered when you were making a decision.

At first, you draw up an initial plan for a project. Over time, even if conditions change, you continue to think of those initial values.

You have our deadlines, budgets, and so on, and you’re not changing your “default settings”. 

If your original plans were too optimistic, anchoring becomes a thing.  

Your initial predictions (even inaccurate) tend to stick around as long as they can

…and this leads to making insufficient adjustments.

And you know what’s even worse?

We prefer to make minor tweaks rather than major changes. Even if major changes are necessary.

How to beat down this issue?

Focus on the real situation and forget what you were thinking first. It doesn’t matter anymore. 

8. Consider the Effect of Social Pressure

There is organizational pressure to be quick at finishing projects

It’s a major reason why the planning fallacy can be so detrimental. 

Workplaces are competitive. They demand finishing projects at an inhuman pace

Workers who appear more enthusiastic than their peers in their time assessments take the lead. Their plans are bigger, better.

Even if their assessments are just less realistic.

Try to stick with what you think about your timing. You know how planning fallacy works, so your dates will be correct. Theirs will fail them.  

Remember that it’s the outcome that counts. 

9. Ask an Unbiased Party to Gut-check Your Plan

If you find it hard to detach from your initial estimates then ask someone for their opinion.

It can be difficult to distance yourself from a plan you’re working on. 

You don’t even have to convince yourself that the ideal timeline you’ve created will work out. We all love to be right. 

Pass your timeline assessment to a coworker. Don’t reveal your predictions. Ask them to give open and honest feedback on it.

How to Overcome the Planning Fallacy

Falling into the planning fallacy makes you feel overloaded.

It’s normal — it’s not your best operating mode

So don’t worry and follow the steps suggested above.

Human brains are deceptive. Take care of yours and lead it to perfection. 

And the best part?

Whatever the outcome, the planning fallacy stems from two primary mistakes:

  • a fallacious plan assumes best-case conditions. No storms or political crises will disrupt construction. You will not get a cold or a last-minute request that derails your plans
  • a fallacious plan fails to consider the data presented by similar cases. Yes, the last three assignments took me a week, but this time I know I can get it done in three days

Here’s the deal:

Recognize and address the planning fallacy before it gets out of hand. 

Don’t let it impact your success.

Don’t rely on your subjective judgment of how long something is likely to take. It’s gonna fail you, anyway. No offense. Truth has to be said.

Measure and compare with your previous, similar performances. What was your subjective assessment of it before? 

Your mind tricked you before, don’t let it trick you again. 

How can you do it next time to make it work better?

Rely on facts, not hopes.

Track your progress and keep working. You’ll get over it with time. 

Tags:: Planning

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