One of the most difficult tasks for many people in IT is providing estimates for project or development work. However, it’s one of those necessary evils that must be performed – often at different times throughout the project.

There’s estimating done up front to price the project and scope out timeframes, there are estimates for change orders throughout the project, and there are often times ballpark estimates given to customers periodically on work they ‘may’ want to be performed.

I’m of the opinion that estimating is more of a gift – you either have it or you don’t. It’s that ability to think somewhat abstractly on given tasks and figure out with some degree of accuracy what the level of effort will be.

Of course, there needs to be a certain level of experience and expertise – but that experience does not always ensure that you’ll give good estimates. Over time, one can learn to be a good estimator, but it helps to have that gift.




Project estimate pitfalls

With all that said, there are many things that can undermine the accuracy or validity of your estimates. Some you have control over and many that you can’t really control. Here are nine common pitfalls that can often negatively impact project estimates:

Poorly defined scope of work

This can occur when the work is not broken down far enough or individual elements of work are misinterpreted.


Simply put, you forget something.

Rampant optimism

This is the rose-coloured glasses syndrome when the all-success scenario is used as the basis for the estimate.




This is when the estimator (in this case almost always the task performer) includes a factor of safety without your knowledge, a cushion that ensures that he or she will meet or beat the estimate.

Failure to assess risk and uncertainty

Neglecting or ignoring risk and uncertainty can result in estimates that are unrealistic.

Time pressure

If someone comes up to you and says, “Give me a ballpark figure by the end of the day” and “Don’t worry, I won’t hold you to it,” look out! This almost always spells trouble.



The task performer and the estimator are at two different skill levels

Since people work at different levels of efficiency, sometimes affecting time and cost for a task significantly, try to take into consideration who’s going to do the work.

External pressure

Many project managers are given specific targets of cost, schedule, quality, or performance (and often more than one!). If you’re asked to meet unrealistic targets, you may not be able to fight it, but you should communicate what you believe is reasonably achievable.

Failure to involve task performers 

It’s ironic: an estimate developed without involving the task performer could be quite accurate, but that person may not feel compelled to meet the estimate, since “it’s your number, not mine,” so the estimate may appear wrong.