How often do you under-estimate how long, what appears to be a relatively simple task takes and then find yourself taking longer, sometimes much, much  longer?

Do you end up taking far longer on what are relatively minor tasks?

How many business projects overrun due to under-estimating how long they'll actually take? According to a report by the Project Management Institute, it’s around 50%.

Under-estimating is a common problem, also known as the Planning Fallacy and one that comes up on a pretty regular basis.

We can all be guilty of optimism bias and it makes us more likely to under-estimate. Not taking into account what might go wrong, forgetting certain elements, the unexpected happens or we get distracted.

When you under-estimate and it takes longer, other tasks get delayed, rushed or postponed. You end up working longer hours in order to finish for the day or get the work completed on time.

Here’s a recent example:

The task: To write a blog post

How it goes ...

• Open up the Draft Posts document and start writing … 
• Remember I created an article on this topic previously … 
• Search my article folder ... find the one I’m looking for … 
• Go back to writing blog post … 
• Think of a previous blog post related to the topic to link to … 
• Check previous blog posts … see a few that need a rewrite … 
• Make a note in the Draft Blog Post document … 
• Update Trello - which ones to rework …
• Go back to writing blog post.
• Step back from the writing for a couple of hours ...
• Come back and finish it off.
• Copy it to be posted … further edits … spellcheck ... readability
• Find a suitable image (often takes a while)
• Hit ‘Publish’.

I estimate an hour or so to write the blog post. Sometimes it can take twice as long, especially if I overthink or spend ages finding the right image!

There are Time blocks in the week for this task. I rarely write all in one go, which isn't a bad thing. Jot down a few ideas, create an outline, expand them when I actually come to write.

How do you estimate how long a task or project is going to take - guess-timate, finger in the air, intuition ...?

We ignore previous, historical information and tend to optimistically estimate our future performance will be magically better, even for the same task.

Improve your ability to estimate

So if you frequently under-estimate, follow some of these tips to improve your estimating abilities:

Set a time for a particular task. Work on it for the allotted time and then move on to the next task. Come back to it later, when you've made progress on other tasks. Avoid getting bogged down in the detail or trying to make it perfect.

Break the task down. Often we under-estimate because we haven’t considered all the steps and sub-tasks involved for that one ‘task’ on our list. e.g. planning and prep time involved before starting the task.

Build in a buffer. Estimate how long you think it’ll take, then add an extra buffer of time. When you complete the task, write down how long it actually took and use that for when you have a similar task. Use your experience and knowledge of past tasks to improve your estimating for present and future tasks.

Apply a ‘faffing’ factor. Based on your optimistic estimate and actual time, what’s the average difference between the two? Factor this in when estimating and add an additional 25%-50% to the estimated time.

When you plan and review each day, you’ll have a way of keeping track of planned and actual.

If you’re easily distracted, switch off all sources of distraction before you start working on the task. Set time limits. Use the Pomodoro technique to help you stay focused. Work on a task at the right time of day when your focus and motivation is highest, and you’re less likely to get distracted.

Do less. But do more of the right things. If you have less on your plate, there’s less pressure to be trying to squeeze too many tasks into too small an amount of time.

Block out time in your day to work on tasks. This could be by project, client, topic and then work on the related tasks in that time block. If you don't use the full amount of time, move on to the next task.

Be less optimistic. Rather than working on the best-case, include an estimate for  ‘what if’, worst-case scenarios and work within a range of best to worst. Estimate the task will take an hour and it could realistically take from 30 minutes to two hours. Go with the longer time. If it takes less time, it’s a bonus. 

Take your energy and concentration levels into account. These change on a cyclical daily, monthly and even annual basis. I can be optimistic about how much I get done in a day and not take into account my energy level or lack of.

Ask someone, especially if it’s not a task you’ve done before. If they have more experience, they’re more likely to be less optimistic about your abilities and provide a more realistic estimate.

Small daily tasks, large scale projects

These work on the small scale of your daily tasks as well as for larger scale, longer-term projects for businesses, where they have a bigger impact and lead to failing projects or lost profit.

When you have limited information about what’s involved in a task, apply the principle used to estimate projects. They’ll take anywhere from a quarter to four times the estimated time! The more information you have the more accurate you can be.

Avoid estimating the time for a task or project, until you know more about what’s involved. Use some of the suggestions above to refine your time estimating ability.

If you want to get better at estimating, be more realistic about how much time you actually have available and how much you can realistically achieve.

Let me know if you find these useful and what works for you. If you'd like more time management and productivity to tips with practical solutions to your daily challenges, sign up for my Time Matters newsletter.

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Creating Effective To-Do Lists (blog post)

7 Signs You're Wasting Time (Download)