Why are Progress Bars so Inconsistent?

Have you ever wondered why progress bars are so wildly inconsistent?  They’ll start off speeding along, then stop for a while, then speed up, then slow down…  The ‘Estimated time remaining,’ is even more notoriously unreliable, randomly going up and down by minutes or even hours.

So why is this?  Well, it’s because progress bars work by measuring the number of individual tasks needed to complete an operation, and then comparing how many are done to how many are left. This results in an uneven progress bar because some tasks take longer than others.

The lengths of individual tasks can be affected by differences in the size of individual files. However, a particular computer may handle different tasks at varying speeds due to differences in its specifications.  Some machines are better than others at some tasks, while being weaker in other areas.

Furthermore, speeds can change in the middle of a task, particularly if the computer is being used for something else, and even if the user leaves the computer alone during a major installation, there’s still the possibility of some of the existing software running the background or doing maintenance.

As such, progress bars tend to be less about giving an exact measure of time remaining, and more making it clear that the computer is still working, as during a process like updating windows or installing new software is in the background, it otherwise won’t appear to be doing anything.

This is a large part of why instead of progress bars, spinning circles or other similar images are often used to convey that the computer is busy and should not shut down or put into hibernation.

Someone who has had to sit and wait through the same loading or installation procedure a few times is likely to know when the bar would normally move faster or slower at a given point.  In fact, if a progress bar moves along too smoothly, that can be suspicious, and is commonly seen in adverts on the internet that are trying to pass themselves off as a Windows dialog box or a program already on your computer.

If you have any further questions about progress bars, or software installation in general, just get in touch.