Is there a way of deciding how large to make a listbox, based on the items that it contains?
Take this example, listing a load of philosophers. Here there could be up to 300 items in the list. That means there could be a lot of scrolling to find the desired item, regardless of the size of the box, so potentially keeping it small would look less overwhelming on the page and might be the option to go with over a larger one.
download bmml source – Wireframes created with Balsamiq Mockups
However, when the contents of the list box are fewer it seems more logical to have a larger box, because you can display all the items (in this case below showing all 15 countries in South America).
How do I decide how many items to have visible in the list box? Perhaps a formula of some sort ({Number of total items}/{something}
) or just a good 'rule of thumb'?
(Note: This is just for example purposes, I know there may be better ways of displaying such information (autocomplete search etc) but for the purposes of this question I am only looking for information about list boxes such as this).