I am looking for some evidence concerning the effectiveness of numbers showing the amount of items related to each single filter. I mean the ones you can usually find on the right of each filter, within brackets. Does this piece of info add any value to experience?

As a user a would say it can stimulate or destabilize expectation, due the fact if I am looking for specific item I would be delighted to perceive I will have a great bunch of possibilities or I would start thinking about another seller/supplier in case of scarcity.



I couldn't imagine why showing filter-result counts would not be useful until you mentioned that users might go elsewhere because you don't have what they want. If that's the case, then the numbers are not the problem; you're not providing what your users need.

So I'd support your use of those numbers on the filters. They convey useful information in an efficient way. If users are abandoning your site because of scarcity, then you have to address that issue separately.

  • You are right. I was wondering if there was any evidence (article, usability study or anything similar) proving they were useful or not. Have you got any idea or link to share? Many thanks for your answer. – Elisa Reinaudo Aug 1 '17 at 15:23

I haven't been able to find any research on the subject, and the only mention I can find of any major group commenting on the use of numbers in this situation is from Nielson-Norman, who mention in an a very off-handed manner that "often, facets also show the number of elements available under each filter, and thus help users avoid zero-search results." https://www.nngroup.com/articles/applying-filters/

So long as real estate is not a concern, I would display the filter appropriately, and work hard to ensure that no filter combination is capable of showing a zero results set (meaning any filter value that would return one is hidden.) This is much easier to accomplish with faceting rather than filtering, a method of reducing product searches by displaying additional selections once a previous filter has been selected. See https://www.nngroup.com/articles/filters-vs-facets/ for a good run-down of the difference between the two pieces.


Having an item count next to a filter element increases the information scent of that element, which then increases user confidence when navigating. From the Interaction Design Foundation:

When the available cues give strong suggestion that a certain path will lead us to our goal, we are likely to pick up on them quickly.

The linked article has sources at the bottom that really go into information foraging and information scent in detail.

Baymard Institute also has an interesting research article looking at Macy's 'best in class' filtering system (they show item counts next to filters).

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