From Nielson Norman Group: https://www.nngroup.com/articles/touch-target-size/
Summary: Interactive elements must be at least 1cm × 1cm (0.4in × 0.4in) to support adequate selection time and prevent fat-finger errors.
As a new parent, I increasingly find myself using my smartphone as my primary computer. Jotting down a note, selecting next week’s meal delivery kits, shopping online, and tracking my child’s eating and sleeping patterns all need to happen one-handed, quickly, while holding this tiny new human. Whether these efforts are successes or failures often comes down to a basic, yet critical detail of mobile design: touch target size and placement.
Adequately sized touch targets are critical for using an interface — let alone ease of use! We’ve all experienced frustration caused by small touch targets: visible, yet unresponsive to our taps — or worse, forcing us to accidentally trigger nearby links. These moments make us feel like gawky giants in a too small world.
Often, this issue is described as a “fat finger” problem because users’ fingers are larger than the desired targets — clumsy cocktail sausages poking at screens. But the fat fingers are not the real culprit; the blame should lie on the tiny targets. Designers who prioritize aesthetics over functionally too often forget to create targets that can be easily and accurately selected.
