Touch target

WCAG 2.2 success criterion 2.5.8 requires 24 by 24 CSS pixels at level AA, with exceptions for targets that have sufficient spacing, for inline links within text, and where the presentation is essential.

Success criterion 2.5.5 at level AAA asks for 44 by 44.

Apple's human interface guidelines recommend 44 by 44 points, and Google's material guidance recommends 48 by 48 density-independent pixels.

The physical basis is the contact area of a fingertip, which is around 9 millimetres — larger than most people expect and much larger than an icon designed at 16 pixels.

Two adjacent 24-pixel targets touching each other are far harder to use than two 24-pixel targets with 12 pixels between them, because a near-miss activates the wrong one.

The WCAG criterion reflects this: a target below the minimum can still pass when it has enough clear space around it, measured as a 24-pixel circle that does not intersect another target.

Mis-taps are worse than missed taps, since an unintended action has to be noticed and undone.

A row of small icons in a table or a toolbar is the pattern where this fails most often, and adding padding is usually the whole fix.

A 16-pixel icon can have a 48-pixel target by giving its button padding. The tappable area is the button, not the graphic.

That separation is what lets a design stay visually light and remain usable, and it is the standard technique.

A link inside a paragraph is exempt from the criterion, because its size is determined by the text around it.

Increasing line height in a list of links increases their targets without changing anything visually except spacing.

Measure rendered targets at a mobile viewport with the element inspector, which reports the box dimensions directly.

Look at close-packed groups: toolbars, table row actions, pagination, tag lists, and the controls in a card.

Test on a real device rather than only in an emulator. A mouse pointer in a device emulator is accurate to the pixel and a finger is not.

Check the controls used most, not only the ones that look smallest. A frequently used target that is marginal costs more than a rare one that is worse.