Sometimes, less is more, and that could well be the case with Unit Converter. Rather than presenting a long list of units for you to pick from, it displays just a few at a time, which you can edit to your liking.

Units are grouped into four broad categories: Basic, Living, Science, and Misc. These are presented as tabs, under which are four unit types. Apart from the Basic tab, you can change what’s displayed under a tab by tapping Favorites at the top. You’re still limited to four unit types, but there’s an extensive list to choose from---not as many as some other apps but enough for everyday use.