I have a slim, single progress bar in my simple search engine. The 100% of the progress bar is all the sources in which the search engine can search in.

Sometimes, more sources can be discovered during the search process.

What should I do in this case?

Some options I've thought about:

  1. Pull the progress bar backwards a bit.
  2. Slow down the progress bar.
  3. Freeze the progress bar.

4 Answers 4


I would lean towards having an indiscriminate progress status along with some textual messages showing "Searching more sources..." or something in those lines that gives a better view of what is happening and adds more value.


According to the definition of "progress bar" here I believe that using an indeterminate progress bar can help you. Here is why:

A more recent development is the indeterminate progress bar, which is used in situations where the extent of the task is unknown or the progress of the task cannot be determined in a way that could be expressed as a percentage. This bar uses motion or some other indicator to show that progress is taking place, rather than using the size of the filled portion to show the total amount of progress, making it more like a throbber than a progress bar (see also barber's pole). There are also indeterminate progress indicators, which are not bar shaped.

Here is an example on Windows:

enter image description here


From your options, the most reasonable is probably to slow down the progress bar, rather than stopping it, so it advances and tells the user the system didn't freeze.

Another suggestion, is to add a secondary goal. Instead of altering the current progress bar, once the goal has been reached (old 100%) you could add a second progress which searches in "just-added sources".

  • Thank you for suggesting new ideas. The problem with the last option is that more results can be discovered once again, during the "new 100%" :)
    – Infinity
    Mar 12, 2017 at 18:42
  • You are welcome :) In that case, a progress bar with a set limit doesn't make much sense, I guess, so maybe use some other kind of indicator, at least for the second round and future ones.
    – Alvaro
    Mar 12, 2017 at 20:45

Progress bars is a way to provide feedback. The first usability heuristics for User Interface Design is the following:

Visibility of system status

The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.

If an initial search is done, the interface should explain so and the progress bar should illustrate it. If an extra search is going on, then an extra progress bar could be provided with an informative message.


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