Designing a form where the user needs to select 3-4 levels of categorization. for this, I'm looking at using 4 horizontal combo boxes (refer image below).

Depending on what the user selects in box A, the options in box B will populate and so on, in C when box B has an option selected. Box A is the starting point and other boxes are disabled unless something in Box A is selected.

However, if the user selects option 1 from box A, there will be 4 levels of categorization, but if they select option 2 from box A there will be 3 levels. this means based on the selection made in box A. there will be either 3 or 4 boxes.

My question is this bad UI? would the number of combo boxes changing based on the input confuse the users? Would be it better for the rest of the boxes to be hidden initially and only appear when the option in the previous box is selected.

enter image description here


2 Answers 2


Progressive disclosure & validation should work just fine in your situation as your dropdown may have different conditions affecting other dropdowns.

In my example, there are still a lot of edge cases to consider and I indented the inputs to somehow signify the relationship.


We can solve this in multiple ways, two ways I can suggest is

  1. progressive disclosure but dynamic based on what user selects. One thing that you have to consider here is the spacing between the dropdowns, as, if you have only two dropdowns showing there will be negative space left, so the spacing can be/cannot be dynamic. Below is eg of how a progressive disclosue might look likeenter image description here

  2. The other option is also a progressive disclosure but with reduced clicks, so the user sees options as buttons instead of dropdowns and just clicks the options rather than clicking scrolling and seeing next options (see below image) enter image description here

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