I've noticed multiple apps/websites (especially travel) make use of putting a number next to a filter to indicate how many results will be returned.

I have some concepts of why this is a useful design pattern to a user (especially if users often obtain 0 results). Reducing the complexity of choices, visibility of system feedback if it updates CTA of applying filters, improving communication & trust...

I would like to understand if there is a more solid why to this design pattern, rather than an 'it just works' or 'other sites do it'.

  • Are you asking the question in general or is there a specific use case or product that will help address the question in a proper context? As the question stands right now it is difficult to know what the answer expected is. – Michael Lai Feb 23 '20 at 22:49
  • In general, I was hoping to gain an understanding if there is a logical reason why websites/apps do it, or if it is perhaps individual to each website itself (I.e it’s come from user testing each specific product, and that was the suitable solution) – JByrne Feb 25 '20 at 18:26

This is a tremendously useful feature for me. On the sites where I use it the most, it can take a lot of thought to come up with the "right" filter. If I make a choice that I expect to cut my solution space by half, and it cuts it right down to 2%, or vice versa, it immediately conveys a ton of information about the situation I'm in.

Also, if I filter on, say, 6 parameters, but after I enter 3 I'm down to zero choices, I can fix my problems before I waste more time.

My experience with these types of filters is mostly on the sites of large electronics distributors. Many of the filter terms come from manufacturers descriptions, and different manufacturers spec things in different ways. The more feedback I can get during the filtering process, the better.


Suppose you need to buy a new pair of office shoes.

You go to your favorite physical store, look around for couple of minutes and to your disappointment you find they only have 1 pair left and it’s not the size that fits.

You go to a second store to buy a shirt. You spend 2 minutes looking around to find that they currently aren’t selling shirts.

How convenient would it be if you knew this information before you invested your time looking around for the particular product?

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