Why estimates are always too optimistic compared to the real time needed to finish a task

Do you recognise this kind of situation: “How long will this task take you?” “Oh just 5 minutes” and half an hour later, these 5 minutes are still not over. The small thing that would only take five minutes isn’t finished yet, but the five minutes are.


Business woman working on a task against the clock


How can this happen? It was such a small task to perform, very simple, like a straight line from A to B. And still, it takes X times longer than you thought it would.

I noticed that this is common in the whole world. When an estimation of time is given on how long a particular job will take, that estimate is always waaayyyy too optimistic.
Apparently, in our mind, something to do goes much faster than in reality. But why?

Lack of information

Sometimes, you don’t have all the information required to make accurate estimations. I noticed that the least people know about a job, the more optimistic they are about how long it will take.


Architect or engineer checking planning and work done


For instance, if you want a craftsman to perform a task for you, like getting something repaired, your house painted etc. you, as the client will be much more optimistic in your estimates than the craftsman or woman.

The craftsman knows what all the different steps are and he can make an estimation based on his broad experience. For sure the time estimated will be higher than what you thought it would be.

The same happens in a work environment. The higher the position of the manager in the organisation, the more optimistic the estimates are on a project or an individual task to perform by an employee. In general, the more distance and layers there are between the management level and the person or team performing the project or task, the more optimistic the estimates of the management will be.

Not looking at the whole process

Another mistake that is often made is to put an estimate just on the most important step of the work but not on the entire process.


Blurred background with modern kitchen and woman preparing coffee


E.g., When you’re cooking a meal, often, you only count the ‘cooking’ time, but not the time that you are cleaning the vegetables and putting everything ready so that you can start the actual cooking.

The supporting steps are also often skipped. E.g. you don’t include that you need to buy the food (going back to our cooking example here) or materials in general, that you need to take all your tools and put them away again and clean up afterwards.

In a work environment, a manager often looks only at the end result e.g. the paper of ‘only’ twenty pages that you wrote, but he or she doesn’t see the hours and hours of research and analysis it took to reach this end result.

Mixing up effort and duration

Another reason why estimates are too optimistic in general is that we don’t make a difference between the workload or the effort it will take to perform a task and the duration.


Business woman with alarm clock working on laptop and holding a cup of coffee


The workload or the effort to get a job done is best expressed in hours; It will take X hours to get a task finished.

Duration, however, is the timeframe in which these hours of effort are done. E.g. You estimate that a task will take you 8 hours to finish. If you do these hours in one day, then the duration of this task is one day. But if you only perform two hours a day, then the duration of this task will be fours days instead of one.

For example, you need to paint a small table. You want to give it three layers of paint, and each layer will take you an hour of work. With all the goodwill in the world, you will never finish in half a day. The paint will need to dry in between, so you will only paint one hour a day, and the shortest possible duration to finish will be three days.

It’s logical, but it’s one of the biggest mistakes to take the duration as equal to the workload or effort.

How to set realistic estimates?

Now that we know what the main reasons are that estimates are always too optimistic, we also know what we can do about it.


Young woman working on laptop holding a cup of coffee


  • Get all the information needed about what a task or project consists of. You can break down the project in all the different steps.
  • Look at the whole process, end-to-end. Take into account every step from the start until the finish.
  • Estimate the workload or effort in a number of hours and look at your schedule to plan when these hours will be performed.
  • You can also track your time while working on a job, so you have an idea of how much time will be needed next time for a similar job in the future.

All this is pretty logical. If you pay attention, you will see that your estimates to finish tasks will be more accurate. Your deadlines will be easier to meet and your schedule lasts longer.

So, in the end, you will have less stress and gain time. And who doesn’t want that?

Your view?



Why estimates are always too optimistic compared to the real time needed to finish a task
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