scrolling - How many items in a carousel should be shown to the user at a glance?

Is there any recommendation or best practice?

The context is that of a web application running on desktops. The number of items is variable ranging from 4 to around 10.

Answer

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  How many items in a carousel should be shown to the user at a glance?

  
  

  -> It depends on the number of items, the size of each item, the context in which you will be using it.

  
  


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  Is there any recommendation or best practice?

  
  

  -> No there isn't. Reason: Because it depends on the number of items, the size of each item, the context in which you will be using it.

  
  

You added that the number of items ranges from 4 to 10. This can be OK, but we really can't tell without knowing the context and the size of each item.

I suggest that you make a mockup, either a drawing or something a little more realistic to give a idea of how it will look like. This way you will probably be able to judge yourself if you are still in the acceptable range for using a carousel.

Also I think your question is a bit 'reverse'. You should first look at what you want to display and then choose an appropriate way to display that information. Not the other way around.